The blockchain gives us some decentralized discoverability. The new/hot/trending listings come directly from the blockchain, and cannot be altered by us. It follows the reddit ranking algorithm.

But yes I agree. Us controlling related videos and the search engine, is basically the same as YouTube. If we want to make a video popular, we can, and that's bad.

Sadly decentralised search for DTube would be a very interesting project, but not something we are willing to spend months of developer time on. If we ever see a good enough decentralised solution for search, we will adopt it, even if it reduces our quality a little.