I don't think you understand my question. STUN is only for setting up the connection. With Trickle ICE etc. But after that, who actually proxies the video that is being sent between the WebRTC endpoints? You need TURN servers for that! Without them, people behind a firewall wouldn't be able to actually receive any audio/video streams from Jitsi. So how would it work without TURN?
> people behind a firewall wouldn't be able to actually receive any audio/video streams from Jitsi.
That part isn't really correct? Most firewalls block incoming connections not outgoing ones so both parties agree on a port, hole punching happens and then there is a connection is formed.