Just anecdotally, Youtube's recommendation system seems effectively self-referential. On virtually any subject I look at, recommended videos seem to cycle between just a few themes or even just a few specific videos. I think there's a logical reason for this. I imagine for a given topic you wind-up with: [broad video] related to [other broad but unrelated video] plus [extremist video]. And [extremist video] related t…
To add on to your point: Given my understanding of how the recommendation engine works, if you watch a video slightly related to a topic, then another video slightly related to that topic, there is a reinforcing effect whereby the engine believes you to be more interested in that topic. E.g. if I watch a video on vegetarianism, then another one, it may strengthen the confidence that I am interested in vegetarianism,…
I'm pretty sure this is true. However, there is one more effective around this. You have to go back and delete your history. I have one youtube identity I maintain for exactly one interest (call "interest X"). I have to essentially scrub everything not related to that from it's history or more and more unrelated crap will appear reliably. Basically, even watch 10% of something means recommendations jump up to 50% of other things even though I have a looooong history of just being interested in interest X.