YouTube search is almost completely useless, I just use Google to find YouTube videos. It does seem to search in the video transcript and the comments (I'm not sure but it seems that way).
YouTube's search results will show you like 10 results of the thing you actually searched for, then resort to a section of completely random video suggestions unrelated to your search in hopes some thumbnail will draw your attention and suck you back in to wasting your time watching videos and being served ads.
I also suffered from this issue for a while but then discovered "Unhook" browser extension, which in addition to many other amazing features (e.g. hide recommended videos/comments) has a feature to hide irrelevant search results. With the feature on I get an endless list of matching results and no junk.
I can't even find a specific channel when I spell it correctly, even with double quotes. I have to go into the filters and specify channels-only, and even then it puts a bunch of wrong results in front of it. Their search on YouTube used to be better, showing results for what was actually searched for. But now it seems like they're trying to drive views to high-performing videos since they now give a single page of results for any query before backfilling the results with a bunch of suggestions that have nothing to do with the search
Up until a few days ago I had a redirect for search that fisabled the suggestions on the search page. Now, if I do that, the search only gives 1, irrelevant, result.
You should be able to just go directly to the channel using the URL if you know the channel name. youtube.com/c/<CHANNEL_NAME>. What on earth they use the distinction for, I don't know, but if it's a user with videos instead of a channel, then youtube.com/user/<USER_NAME>.
lol- my thoughts exactly. How can Google search be so good, while YouTube search is so abysmal? Google bought YouTube in 2006, so they've had 16 years to get it right :D
