Youtube Video Screenshot Tool от person4268

This will add a button in every YouTube video's settings menu that will let you take a screenshot of the video. The screenshot will be taken at the video's selected resolution and will only include the video itself, no captions or the player bar, and opened in a new window.

Note that some ad blockers may try to close the window right after it opens. If that happens, either disable your ad blocker or reconfigure it.

Source code available at https://github.com/person4268/youtube-video-screenshot-tool