That's only because for video chats you need a full mesh in p2p. There's no requirement for that in webrtc itself which would be just the transport protocol in your case. You can also send only the selected chunks rather than stream the whole file.
The whole premise of this thread is the speculation: "Google would eventually try to deprecate whatever API peertube needs". My answer to that is "basically do what webtorrent already does" (but using a different API)
