Hosting video requires a lot more resources than hosting text, hyperlinks, or even pictures. It might be too much for individuals to self host video on a scale that could even distantly resemble how we use youtube today.
Then again, maybe there are ways to make that burden smaller. IIRC Peertube does do some p2p stuff to try and share the burden a bit but I’ve also heard that it’s not really feasible to rely on that to scale.
For small-scale stuff like that it will surely work. It’s unclear if it scales to youtube volumes. Maybe it doesn’t have to though, small scale stuff is valuable too.