I have always felt this is where recommendation engines go wrong.

If I watch a cat video, it'll think all I like are cats.

I may like content about Foo — something entirely unrelated to cats — if I watch it. But since I have never watched anything about Foo before (perhaps because I didn't know about its existence), it won't recommend me Foo. Therefore I wouldn't know it exists. Hence I never see it, even though if I had seen it I may (or may not) have liked it.

Meanwhile, after a point I get tired of all the cat videos, and stop using the service.

I want recommendation engines to occasionally recommend totally fresh content unrelated to anything I ever watched.