I'm not sure that fully explains it here. I see more relevant search results below the "People also watched" section (just checked now). Further down, there is also "For you" and "Previously watched" which have videos of no discernible relevance to the query and these are also followed by again more relevant search results.

No, youtube will cut off your search results early to show you videos it think will engage you more regardless of how many search results there actually are.

Google does not give a fuck what you think you want, because they know better than you