True, but Youtube suffers from its own class of usability issues around ads/video. Eg. the other day I was watching a YT video and noticed that the top-voted comment was a particularly weird/creepy comment - so I absent-mindedly clicked the "thumbs down" next to it. Suddenly I was whisked away to a login page with no warning, interrupting the video. I immediately clicked "back" - and was forced to re-watch the entire ad before resuming my video. Stuff like this infuriates users - I'm trying to actively engage, and being punished for it?!