The biggest problem with videoconferencing is using movie video codecs (designed for maximizing compression, and not for multicast latency control) tuned/tweake

The biggest problem with videoconferencing is using movie video codecs (designed for maximizing compression, and not for multicast latency control) tuned/tweaked for the worst client. So the typical video conference server uses a hand tuned gstreamer and a mechanism for requesting key frames at the pace of the slowest client. That work okish for up to few hundreds of connections in the case of all peers having quality connections (fiber). Scalable video conference, with e.g. thousands of concurrent clients require a different problem approach, being solved eventually because of specialized video hardware acceleration in the video conference gateway server, changes in the network infrastructure, and also low latency devices at client side.