I don't feel like anyone has gotten recommendations right, even though one seemingly obvious approach has not been tried by anyone: allow ratings of favorite works across all media: movies, tv shows, books, music, radio programs, youtube videos. Make a very easy, efficient UI to add ratings. This way you will avoid superficial matches: if I just watched an excellent steampunk cartoon, let's offer a zillion of throwaway crap steampunk. It's not the steampunk part that I liked, it's that it was amazingly done.
If I was a huge fan of books, movies, music, youtube picks of another user, it may be there is a deeper connection of the kind of quality we are both looking for, and so his or her recommendations would be highly relevant.
Recommender systems moved from explicit feedback (like ratings) to implicit feedback precisely because users are less likely to actually rate stuff and also because ratings are subjective; by which I mean your interpretation of 3 stars(good) may not agree with mine(average). I have watched tons of movies/shows on netflix or videos on YT for that matter but have not rated a single video.
To address the other part of your suggestion i.e collapse ratings/feedback across media like movies,books,etc. usually it is very difficult to have a dataset that spans multiple media across the same set of users. Even if it is present it would be too sparse (more sparse than usual for a site like YT with a continuously changing content library) to actually help. Though I agree that if anybody can get the recommender right, it is Google with the sheer amount of info it has on each user.
You're kind of suggesting people go in reverse. Ratings were the initial way these things worked but then they moved to more implicit signals. Netflix used to be all about star ratings back in the day; now they want to measure what you're actually watching.
I think the issue of a system determining whether you like the steampunk genre vs the quality of only that particular steampunk video is separate from the issue of ratings.
But also view-time or view-count don't tell the full story of how much you liked that video.
I am not happy with YT recommendations because they suggest crap videos to me and not the finest one available for that topic, just as he said.
The system should rather suggest me a different topic but with the best quality/content available, rather than a super similar video with crappier quality/content.
If I was a huge fan of books, movies, music, youtube picks of another user, it may be there is a deeper connection of the kind of quality we are both looking for, and so his or her recommendations would be highly relevant.