TL;DR: Technically, the SO and YouTube licenses are (probably) incompatible, so if you want to use copyrightable elements from SO in a YouTube video, you'll have to get permission from the original author. Certainly it never hurts to ask, even if you might not strictly need it.
You cannot change the YouTube license…
When you upload a video to YouTube, you have to choose between one of (currently) two licensing options: "Standard YouTube Licence" and "Creative Commons – Attribution".
Neither of those licenses is exclusive, so you're certainly allowed to also license your video (to YouTube and/or anyone else) under some other terms. (That's what the answer you linked to means by "[stating] a license in your video description".) But even if you do so, your original license grant to YouTube still applies in addition to the other license. You can't just turn around and say that haha, no, you were just kidding, it actually doesn't.
(And if you try to do that, and actually get someone at YouTube to notice, their most likely response is to simply take your video down. They're a huge company with millions of uploaded videos — they're not going to care about just one video, or even one channel, at least if it doesn't happen to be one of the handful of their most popular ones.)
…and you must license derivative works of Stack Overflow content under CC BY-SA (not CC BY!)
According to the Stack Overflow Terms of Service, "subscriber content" on SO (and other Stack Exchange sites, including this one) is licensed under the Creative Commons Attribution–ShareAlike license (CC BY-SA, version 2.5, 3.0 or 4.0 depending on when the content was posted). The "human-readable summary" of this license, as shown on the linked page above, says (emphasis mine):
You are free to:
- Share — copy and redistribute the material in any medium or format
- Adapt — remix, transform, and build upon the material
for any purpose, even commercially.
Under the following terms:
Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
ShareAlike — If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original.
No additional restrictions — You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits.
Note that this is not the same license as the Creative Commons Attribution 3.0 license (CC BY) offered as one of YouTube's licensing options.
In particular, the CC BY-SA licenses include the "viral" ShareAlike condition, which requires any derivative works based on the licensed work to also be licensed under the same CC BY-SA license (or one of a handful of designated "compatible licenses"). So if you e.g. make a derivative video based on a CC BY-SA license Stack Overflow post, you must also license your video as CC BY-SA in order to be allowed to distribute it at all.
…and you (probably) can't just dual-license your video to YouTube either
In principle, there's an option that might be allowed under the terms of CC BY-SA, and would at least seem to follow the spirit of the license:
- Upload your video to YouTube normally, selecting "Standard YouTube Licence".
- Also license your video to the public under CC BY-SA 4.0, e.g. by stating so in the video description or in the video itself.
The idea is that, by explicitly releasing your derivative video to the general public under CC BY-SA, you've followed the requirements of the ShareAlike clause of the original Stack Overflow content's license (with some possible caveats regarding downloadability — see below). The remaining question, then, is whether you're allowed to also license the video YouTube itself under their standard license. And this, in turn, effectively boils down to the following question:
Does the standard YouTube license allow YouTube to do something with your video that CC BY-SA doesn't already allow them to do anyway?
If it doesn't, then the YouTube license grant is redundant: you're just telling YouTube "sure, I give you permission to do all these things that you already can do under CC BY-SA."
If it does, however, then it's likely that you are not legally allowed to grant YouTube such permission to use your video, since it's (presumably) a derivative work of SO content it's based on, and thus may not be legally distributed without the original copyright holder's permission (which you and YouTube, again presumably, only have in the form of the CC BY-SA license).
The tricky part here is finding out exactly what the "standard YouTube license" actually says. As far as I can tell, the actual terms of that license are buried in YouTube's Terms of Service, and basically say the following (plus some other stuff regarding monetization and content deletion that do not seem relevant here; emphasis again mine):
Licence to YouTube
By providing Content to the Service, you grant to YouTube a worldwide, non-exclusive, royalty-free, transferable, sublicensable licence to use that Content (including to reproduce, distribute, modify, display and perform it) for the purpose of operating, promoting, and improving the Service.
Licence to Other Users
You also grant each other user of the Service a worldwide, non-exclusive, royalty-free licence to access your Content through the Service, and to use that Content (including to reproduce, distribute, modify, display, and perform it) only as enabled by a feature of the Service.
As far as I can tell (and keeping in mind that I am not a lawyer), the "licence to other users" is innocuous — it's just a subset of the rights already granted by CC BY-SA. (And none of these license grants are exclusive, so they don't prevent you from also granting a more permissive alternative license, such as CC BY-SA.)
Most of the "license to YouTube" also looks fine to me, insofar as it basically just allows YouTube to distribute the video on your behalf, which, again, CC By-SA already allows anyway. Mere mechanical modification of the the video for display purposes (such as downscaling it to a lower resolution, adjusting the playback speed, etc.) also does not seem particularly problematic to me, as such mechanical changes are generally not sufficient to create a new copyright, and thus your CC BY-SA license grant should extend to such mechanically modified versions as well.
However, there are a couple of terms in the license, which I've highlighted in bold above, that may be read as allowing YouTube to create further derivative works of your video (and thus, potentially, of the SO content it is based on) e.g. for promotional purposes, and to release these derivative works under a license other than CC BY-SA. That would be a violation of the ShareAlike clause, and thus something that you may not give YouTube permission to do on behalf of the original SO content creator.
Would YouTube actually do that with your video? Most likely not. Could they? Under that license, yes they could.
Also, there's a potential issue with the clause in CC BY-SA 4.0 that says (in section 3(b)(3)):
You may not offer or impose any additional or different terms or conditions on, or apply any Effective Technological Measures to, Adapted Material that restrict exercise of the rights granted under the Adapter's License You apply.
The problem here is that YouTube does not normally permit downloading videos, and has been known to send DMCA takedown requests against software projects such as youtube-dl that attempt to circumvent this restriction. As such, only distributing your video on YouTube could be interpreted as an attempt to prevent viewers of the video from exercising their right under CC BY-SA to download, redistribute and create derivative works of it.
Also, even if you e.g. included an alternative download link in your YouTube video description, that might not be sufficient to make you compliant with CC BY-SA, since you would still have granted YouTube a license to display and redistribute your video as they want, including in contexts that do not include your download link.
…but your video might not be a derivative work in the first place
However, all is still not lost, and in practice you might well be able to legally create a YouTube video based on a Stack Overflow post anyway.
The first, obvious, question is whether your video even counts as a derivative work in the first place. Ideas cannot be copyrighted, and if all you're taking from the SO post is the idea, while not copying any specific phrasing choices or images or code, then your video won't be a derivative work under copyright law, and as such, you won't be bound by the restrictions of the CC BY-SA license.
Also, even including e.g. small snippets of code may be permitted without turning your video into a derivative work, if either the pieces are simple and generic enough not to meet the threshold of originality required for copyright protection, or if your use of them in your video is permitted under fair use (US), fair dealing (UK and commonwealth) or similar legal doctrines in your local jurisdiction. In such a case, you're legally allowed to use them in your video without availing yourself of the permissions granted by the CC BY-SA license, and thus also without being bound by the restrictions included in that license.
The tricky bit here is that the boundaries of copyrightable originality and fair use are notoriously blurry and vary between jurisdictions, and it's very hard to be sure on which side of them your use falls on without an expensive and uncertain legal process. When in any doubt, I would thus recommend not relying on them too much, at least not if your use is such that you could possibly imagine someone wanting to sue you over it.
By the way, one of my own answers on Physics Stack Exchange was actually turned into a YouTube video by the "It's Okay To Be Smart" channel a couple of your ago. What they did was exactly this: while they followed the style and structure of the answer quite closely in many respects, they took care to rephrase everything in their own words and to recreate all the demonstrations and diagrams.
Is their video legally a derivative work of my answer? Maybe, marginally — some of their diagrams look very similar to mine, and some of the similarities just might be distinctive and original enough to be copyrightable. But even if I wanted to sue them, this would be a tough argument to make and the outcome would by no means be certain.
I do wish they'd at least included my name and a backlink, though. :/
…or the author of the original SO post might have multilicensed it
Even if your video is a derivative work of an SO post, you might still be able to use content from the post in it without relying on the CC BY-SA license. In particular, the same content might also be available under another, less restrictive license that you can choose to follow instead.
In some cases, the post your quoting might directly include an alternative license notice e.g. as part of a code snippet, making that snippet (or whatever the extra license notice applies to) dual-licensed.
The code, images or text that you want to use may have been published elsewhere under a different license by its author. For example, you might find a copy of it on one of the author's GitHub repositories (example), or it might have been reposted on the author's blog. Or, in the case of code, it might actually come from an open source project available under a permissive license (example).
(BTW, both of the linked examples above are also examples of code with explicit license notices on SO).
In the absence of an explicit link in the post, Google can be your friend here. Just make sure that any versions with a different claimed license really are licensed by the author and not just unauthorized third-party copies.
Some Stack Overflow users, such as myself, include a general dual-licensing statement on their user profile. Mine, for example, currently looks like this:
Please consider any (original) code I post to Stack Overflow and other Stack Exchange sites to be released under CC-Zero unless stated otherwise. You may do whatever you want with it and don't have to credit me in any way, although of course that would be nice.
In addition, to avoid ambiguity regarding the open source status of CC-Zero, you may also use, copy, modify, and/or distribute any original code I have posted on any Stack Exchange sites under the terms of the ISC license or any other OSI approved open source license, unless explicitly stated otherwise. If doing so, please use the copyright statement "Copyright <year of posting> Ilmari Karonen" if no other copyright statement is provided.
(Disclaimer: the statement above has been written by me for my own use, and has not been reviewed by a lawyer in any jurisdiction. If you like it, you have my permission to adopt it verbatim or paraphrased for your own use, but I make absolutely no warranties regarding its legal effect or validity.)
…or you could just ask for their permission
Obviously, this is always an option, assuming that you can contact the author. One simple way to do that is to post a comment on the post you want to reuse, asking for explicit permission to use it in your video and/or for an alternative license with more permissive terms. Of course, it's up to the author whether or not they want to grant such permission.
At a minimum, something like the following additional permission should be sufficient (noting, again, that I am not a lawyer and that the text below has not been reviewed by one):
In addition to the permissions granted by the CC BY-SA 4.0 license (and incorporating the definitions therein), You may upload Adapted Material based on this Licensed Material to third-party content sharing sites such as YouTube, and in doing so grant such sites an additional separate license to the Adapted Material and any Licensed Material contained therein, as required by their Terms of Service, provided that:
- You follow the License Conditions of the CC BY-SA 4.0 license (including the requirements to license the Adapted Material under CC BY-SA 4.0 or a BY-SA Compatible License, and to indicate this to recipients in a reasonable manner), and
- You make a reasonable effort (e.g. by providing an alternative download link, if the content sharing site does not provide one by default) to allow recipients of the Adapted Material to download it in a manner and format that allows them to easily exercise their Licensed Rights to it.
or, in non-legalese:
Yeah, sure, you can make a YouTube video based on my SO post, as long as you license it under CC By-SA and include a download link in the video description.
…and they might not care enough to sue you, anyway
All things considered, it's extremely unlikely that anyone would bother to spend the time and money to actually sue you over a video based on a Stack Overflow post.
At worst, if they really didn't like what you did, they might decide to send YouTube a takedown request for your video, since that's a relatively simple process. At that point, assuming that YouTube acts on the request and takes your video down, you basically have three options:
- cut your losses, let the video stay deleted and hopefully be more careful next time,
- contact the author of the source material and try to come to a mutually acceptable agreement with them (which, of course, you should ideally have done before posting the video), or
- if you really believe that your use of the SO content was not a copyright violation, you can submit a counter-notice to YouTube (who will forward it to the original claimant, who will then "need to respond with evidence that they’ve taken legal action to keep the content from being restored to YouTube" within 10 days).
Of course, ideally you wouldn't ever let things get that far in the first place. And the way to do that is to follow the advice above, and specifically to:
- not reuse copyrightable content when you can easily avoid it, but instead express your ideas in your own words, and with your own pictures and code;
- when you do want to reuse content created by someone else, ask their permission if possible;
- when basing your work on freely licensed content such as SO posts, try to follow the spirit of the license as far as possible, even if you cannot technically follow it to the letter;
- in any case, always give credit where it's due, both for (potentially copyrightable) content and for (non-copyrightable) ideas and inspiration; and
- generally try to be nice to people whose knowledge, creativity and hard work you're building on.
Of course, following this advice won't prevent someone from suing you for copyright violation (although it might in some cases reduce their chances of prevailing, and/or the damages they can successfully claim if they do). But it makes it less likely that they'll want to.