It takes a while to load, but a ton of info here on video conferencing technology.
http://myhome.hanafos.com/~soonjp/vchx.html
I am particularly fond of:
Randy Cole, "PVP - A Packet Video Protocol", Internal Document, USC/ISI, July 1981.
"The Packet Video Protocol (PVP) is a set of extensions to the Network Voice Protocol (NVP-II) and consists mostly of a data protocol for transmission of video data. No specific changes to the NVP-II protocol are necessary for the PVP."
1981. packet video... (um, IP network is a packet network!). Transmission of video data.
:-)
Alex