Since it's all peer-to-peer, there isn't anything being done on the server (I don't even think there is a server?)

Like others have said, the bottleneck will be your client's upload speed- if you have a meeting with 10 people, you're going to be sending your video out to 10 different peers.

Can't you send 1/10 to each, and they will in turn send to one another, so the load is equal on all nodes?