it's sad that every single comment on the video are supportiveI would be willing to state that YouTube is FOS.
Folks on a hobby forum are, by and large, trying to share information and do so for the benefit of the hobby and for the object of the hobby (here, fish and corals and such). Forums are specifically designed to be structured to do this well -- everyone can contribute equally; claims can be rebutted; evidence from other sources (other forums, journal articles, reports of personal experiences, photos, etc) can be brought to bear on discussions; each and every claim can be tagged by any other forum user with a somewhat precise reaction (the emojis), and these individual and precise-ish tags are archived with the post they refer to. Forums are an information sharing network. The algorithm feeding users content on a forum is 'new content'; there is also a search tool that simply searches keywords (maybe ranked by some combination of post date/popularity/keyword frequency). Also, moderators keep out the majority of trolls and bots, and others are publicly if sometimes subtly flagged by regular users.
Folks posting videos on YouTube are, by and large, trying to get views. They do so for all sorts of reasons. Views come not only from accurate or wise information (and this only rarely, and not by design), but also from wild or contentious or flashy (high production values make patent BS a lot more palatable) or conspiracy-supporting or fashionable or generally 'clickbait-y' content. The specific claims in videos cannot, for all practical purposes, be rebutted -- because comments sections are chaotic in general, because video posters are not expected to reply, and because repliers don't have the same status as content posters . The extent of the archived tags that can be added are to the video as a whole, and not to specific claims, and these are only 'yea' or 'nay'. YouTube is not a network of users, it is a series of megaphones given only to certain people who use them to yell at the audience. The algorithm feeding users content is designed to play into the worst aspects of human psychology, and also to get the user to view more videos regardless of the merit of those videos. Trolls and bots are not removed from the comments.
Forums are for sharing information. YouTube is for entertainment.