ISTM there could be some opportunities here? First, not everyone is talking at once (else this is a riot rather than a conference), so many of the uplinks could be "nothing new" packets for much of the time. Second, if any participant(s) (even a dummy participant) has faster uplink, that/those client(s) could forward to the rest of the group, in a fashion somewhat analogous to torrent.
You could also do leader election and make that one leader be the sink. Then broadcast to everyone else. However, I'm gonna keep my trap shut because I don't want to get downvoted by this elite squad of video professionals.
