Video conferencing with Jitsi

From https://jitsi.org/jitsi-videobridge-performance-evaluation/ it sounds like the key for scalability is the "last N" mode. The bridge receives streams from all participants, but only broadcasts the streams from the N most recent "dominant speakers". That means the bridge's traffic scales linearly with the number of participants, and a client's traffic scales with N (which is a small constant).

If you don't use that mode then I think it's O(num_participants^2) on the bridge and O(num_participants) on the clients, though with better constant factors than peer-to-peer: each client only has to upload their stream once to the bridge (vs num_participants-1 times to every other peer), which is good since clients usually have much lower upload bandwidth than download.