My experience has been that when the network is blocking or not allowing the video chat, the error message will make specific reference to the fact. I tend to doubt that is the problem.
If you haven't seen it yet, take a look at the following. KB26096-Troubleshooting Wi-Fi and networking on the BlackBerry PlayBook
That isn't specific to the video chat app, but it should help with troubleshooting the wifi connection. That is where I would start. See what others say. Posted via BlackBerryForums.com Mobile