interesting, there must be some variation in the algorithm.

I have just loaded Youtube and in the 8 recommendations above the fold :

- 4 of them are from my subscriptions

- 1 is the last published in a series of videos I have been watching, published 2 hours ago

- 1 is from a channel I have never watched AFAIK, but contains a sketch from a comic duo I watched often on Youtube

- leaving 2 lectures that don't come directly from what I watched recently.

If anything, I would prefer if Youtube was pushing way more original topics.

One thing I have remarked is that their algorithm is very "grippy". Once it identifies a topic you might be interested in, it makes sure to find other videos on the same topic.

As an example I stumbled on a beautiful video about what life is like for an man with autism. The next day Youtube recommended me a video where women with autism talk about their lives (actually I remember having already watched that video several years ago, so a meh recommendation). Today Youtube wants me to watch a video about autistic children in China.

Also, with the magic of A/B groups, we might be running on 2 very different algorithms for all we know.

> even a naive recommendation engine would perform better.

I think you are underestimating the complexity of the problem :)