So Cal Free Net.org

I just moved to C street between the 24th and 25th, and I got so glad when I figured out the neighboorhood has free internet access.
I have an Mac computer and I get my signal through the airport, but when I try to use the video-conferencing program that comes with the Mac OSX, the iChat AV, I am never able to conduct a video conferencing (nothing wrong with the text messenging tough).
I open all the ports necessary on my personal firewall, but I still can get it working. I think it might be something at the Nodes... maybe some kind of embemded firewall?!
Does anybody know anything about that?

Thank you so much

Fabiano