I often find myself getting this kind of random glitch while playing YouTube videos.
It's either happen in the middle of a video (like the example above) or in the few first second of a video. When it is the latter, the video usually restarts for a few times then shows the typical YouTube error (video cannot be loaded).
As you can see from the thumbnail (and you can try to open one example yourself), it's not the problem from the video. My uneducated guess is there is a problem with my GPU. But I don't know what to do.
My card is up-to-date and the problem mostly only come from playing YouTube video. I don't recall having this with media players (Windows Media Player or VLC) or image-editing/video-editing softwares like Photoshop or Corel Video Studio.