I am not a lawyer; I am especially not your lawyer; this is not legal advice; if you want legal advice, hire a lawyer.
But probably not.
The YouTube terms of service seem to prohibit this pretty clearly:
You agree not to distribute in any medium any part of the Service or the Content without YouTube's prior written authorization, unless YouTube makes available the means for such distribution through functionality offered by the Service (such as the Embeddable Player)...
You agree not to access Content through any technology or means other than the video playback pages of the Service itself, the Embeddable Player, or other explicitly authorized means YouTube may designate.
Now, were YouTube itself licensing the videos in question under the CC license, they might be prohibited from enforcing that term:
You may not offer or impose any additional or different terms or conditions on, or apply any Effective Technological Measures to, the Licensed Material if doing so restricts exercise of the Licensed Rights by any recipient of the Licensed Material.
though I'm not sure if the language in question would apply. However, it seems likely that in most cases, YouTube is using the material in question under the license to which users agreed when they created their accounts, and therefore is not bound by the term in question.
All that said, it's entirely possible that the clause in the YouTube ToS prohibiting downloading does not apply for whatever reason (unconscionable in a contract of adhesion, browsewrap agreement doesn't form a contract to begin with, it's superseded by either some other agreement (part of the API EULA, etc), it's contrary to some law in your jurisdiction, etc).
Just to be very clear, though, there is no COPYRIGHT CONCERN preventing uses like the one you mentioned.