It’s a mess. You first run into bandwidth problems on the incoming streams. But you also run into a problem with the device support matrix.

If you say “We’ll support H.264, H.265, AV1, AV2” and “We’ll support 480p, 720p, 1080p, 4k”. Now you’d be asking the clients to do 16 different encodes to upload.

This gets more complicated if you add more streams or supported formats. You also end up needing to coordinate that with the client.

AFAIK, the way youtube currently handles this problem is they have dedicated encoders for live streams and fast encoding. For popular videos they do a second step where they do a more full matrix to optimize viewership.

IDK what youtube does for storage (if anything).

A service like youtube is simply hard to pull of with bailing twine and string (like lemmy).

A core part of the service that youtube offers is re-encoding uploads. That requires some beefy hardware to serve even a moderate number of people.