I believe that two-way video and audio (as well as conference video and audio) are iChat specific features, and that they are only available between iChat users.
Just tried it out; video/audio two way. Yay.
It seems like one-way video would be sort of like voyeurism… or exhibitionism, depending on which way it went. :o)
@Grisson Heh; it was the audio that wasn’t working, so I was confused.