someone is about to make a lot of money.
Not that I have thought too terribly deeply about this, but I have a suspicion that this feature is actually powered by additional metadata sent along with the video by the content provider. It seems logical that if you were to control a vast archive of rapidly growing, extremely similar looking content, you would want to tag just about everything you could about it so you could build product.
I predict there will shortly be some dark future for all of us where we'll be able to don our Facebook nightmare helmets, say a single word, and have a super focused stream of filth blasted directly into our brains like that one scene from Demolition Man. That's where this is all going, right? Gotta be.