The random frame may be a poor choice of representing the content to the point of being worse than a photoshopped thumbnail.
It's definitely a problem. Clickbait thumbnails blatantly misleading people into clicking. It comes down to poor link integrity, which Google was apparently against at one time, now they basically encourage it.
There's great stuff on youtube, but the trash pile is bigger than ever and gets more clicks.
The classic example one of the oldest custom thumbnails on youtube that I recall, is that roller-coaster in mid air. Millions of views, as people clicked to see a coaster they didn't know existed. Of course, the video has no such coaster, and as a result thousands of dislikes. But who cares about dislikes when you have 40m views and counting on a rubbish generic video with misleading thumbnail.
