Zoom: fourteen people, three continents, one room

How video meetings work for 300 million daily meeting participants: a small, ordered control plane with one controller per meeting, kept apart from a media plane of routers that forward packets without decoding them, senders that send layers so each router can pick one per receiver from its bandwidth estimate, UDP with forward error correction, resends and jitter buffers and TLS on 443 through firewalls, and participants placed in their nearest zone with routers cascading across regions.