Although you have an answer and you have selected it as the correct answer, I'll tell you what is the real world situation.
Although, the "Standard Youtube License" or TOS reads
"You shall not copy, reproduce, distribute, transmit, broadcast, display, sell, license, or otherwise exploit any Content for any other purposes without the prior written consent of YouTube or the respective licensors of the Content."
you can use it fairly, if it isn't meant for commercial gain for you and you use less than 10% of total content. taking a picture of a video, say 10 minute long video, is definitely less than 10%
Everything is below the law of a country. Each and every country has some law called "fairuse" of copyrighted material. It's there to allow any body to use a fraction of original copyrighted material and not to face jail time for doing that. Thereby, the TOS of youtube is bullshit if it doesn't say anything about fairuse and is just there to inform you and most accurately "scare" you to prevent using the material unfairly.
For an instance, what if an icecream shop owner actually write a TOS, "After eating the icecream, you must jump over a cliff", is it fair? is it right? is it following any government imposed laws? no right? But he can write it in her/his TOS, just to inform some bullshit he wants to convey to the customers. No one needs to follow anything written in the TOS or agreement if it doesn't abide to the laws imposed by the country's government.
The truth is you can use it fairly and the general legal point of view is if someone creates something original and no body else should ruin the ownership and benefits such as fame, financial gain etc etc which is supposed to receive to the original creator.
In my point of view,
Violating copyright examples
- Getting a 10 minute video, taking 1 screen shot, and saying that
this is a screenshot of your own video, making others believe that
the owner of the original video is yours or you created this image
(not revealing the screenshot you're showing is of an actual video
which someone else owns)
- someone created a drawing and videoed it and you took a screenshot and calling that this is a drawing you created or exposing it to public that the original creator of the video only wanted to share the video with his choice of people.
Not violating copyright examples
- Getting a 10 minute video, taking 1 screenshot, and tracing or
cropping something specifically commonly found in nature, such as a
1 apple tree out of the 20 other apple trees of your screen shot
from the video.
- Someone created a drawing and videoed it and posted it in youtube for public viewing and you took a screenshot and posted it on facebook by saying "Hey I found a great video of a drawing, here's the original link to the actual video" with the link.
- Getting a 10 minute video which is available for public viewing, taking 1 screenshot, and tracing or cropping something in the screenshot and using it to educate your child or group of children in the school upto grade 6.
Most important thing to keep in mind.
- Copyright law is there to prevent and give a good lesson to the crappy people from using someone else's property unfairly.
- Fairuse law is there to prevent and give a good lesson to the crappy owner of an actual original content to show that she/he can't just own everything and restrict people from using it fairly.
Thank you and no need to select this as an answer. Just wanted to increase the intelligence of people.
P.S: I don't mind getting negative votes, as I have revealed the truth about real world.