My guess is it's because it's a similar role to a Reddit Admin, which is to say they're basically a global moderator. Also, having access of any kind to the site's SQL server requires an element of trust. That's probably why they require the video interview.
You're right about the forums. While they're useful as smaller chat rooms separate from the "main ones" (for example, someone in a Discord server I know started a forum for fanart and discussion about a specific upcoming video game), they're completely useless as a replacement for traditional forums.
Also, like you said, the search feature simply isn't good enough to be able to efficiently search through all those forums. While Reddit's (and probably Lemmy's) search engine isn't great either, it at least has the benefit of being indexed by other search engines.
Yeah, the dislike bar used to be a thing. You could see how many dislikes there were compared to likes, all represented on a line below the two buttons. It was sort of like this image, except imagine the "yes" and "no" as a single line (but retaining their separate colors).
They're at least understandable (usually), but they're like 5-10 seconds behind the video (sometimes longer), and they can be difficult to interpret at times.
My guess is it's because it's a similar role to a Reddit Admin, which is to say they're basically a global moderator. Also, having access of any kind to the site's SQL server requires an element of trust. That's probably why they require the video interview.