I cant recall what the port was... A serial port? I cant recall - but just that it was on all O2s and it was just knocking out the plastic cover to get access to it.
The base model supported audio and "moose cam" (A webcam, in 1996!). If you paid extra you got video.
You could buy the base AV1 "analog" video I/O card and then plug an SDI expansion breakout board (I think the Miranda VIVO was the most popular) into the webcam port, instead of buying the much more expensive AV2 "digital" video I/O card.