There's a wiki program that natively uses a version control repository, Fossil. You can fork a Fossil wiki and contribute updates back to the original.

It wouldn't be too hard to for example create a few Fossil repositories for different topics where the admins on each are subject matter experts (to ensure quality of contributions), and then have a client which connects to them all and with a scheme for cross linking between them

Peertube already exists for video, it's more like a different take on bittorrent.