I would love for something to replace YouTube, especially something in the Fediverse, but video unfortunately has much higher storage and bandwidth requirements, so it’s hard to imagine that not being totally cost prohibitive at high levels of traffic, even if it’s split across so many different servers. I’d love to be wrong on that, though.

Yeah. A shorter-term solution might be a browser plugin that recognizes links like that and converts it to a hyperlink to that community on whatever instance you tell it. I’m not a programmer but that does seem like a relatively simple plugin for somebody that actually knows what they’re doing.