Maybe recommendations are harder than we think because our tastes are too arbitrary and unpredictable. Maybe overlapping with someone else's tastes actually predicts nothing about whether there are any more places we will overlap, so it's not the simple data processing problem that we wish it to be. I've tried all sorts of "people who liked X also enjoyed Y" book and movie lists and it never seems any better than a g…
Also, what appeals to us is heavily dependent on our mood and situation at the moment. There are many times when something appeals to me heavily one day, and not at all another day.
Even on those different days, I can still recognize a show that I might like to watch on another day though.
On youtube I put those in my Watch Later list.