That overengineered isight camera worked through multiple adapters up until the introduction of the M1, when they sadly finally removed the driver. I used to use it connected to my intel macbook pro for meetings in the the late 2010s for fun.
This is awesome! I remember trying to figure out how this worked as a kid, and never made headway. Today my dream was realized. ;)
SNATMAP is essentially Apple's version of STUN (RFC 3489, also 2003): learn your public IP and port from an outside server, swap them over chat, then both sides send packets at once to punch through NAT. That's why port-preserving NAT matters. Carrier-grade NAT, common on mobile and some ISPs, assigns a new port per destination and breaks it. Modern WebRTC falls back to a TURN relay, but iChat had none, so if calls still fail after the hosts fix, check for CGNAT on either end.
A time warp to when video conferencing actually worked, as opposed to every new release of FaceTime now being some kind of avant-garde art experiment with the UI being increasingly impossible to use for both technical and non-technical users.
The last straw for me was making the recents/contacts as confusing as it was, and I personally made some accidental calls to former contacts that for some reason were made front and center.
I expect the next version will hide even more controls behind a new, indecipherable icon that looks like a 2D abstract pair of testicles.