jitsi is an open server.  it makes connections to you when you want to chat with video, and for each person in the room.  it then delivers everyones video to each user, eliminating bandwidth issues caused by other video network topologies.
its neat. its called SFU architecture - and when you start getting serious about optimizing it, you end up reading things like this:
https://webrtchacks.com/sfu-cascading/

David Medina