You need to use server for video chat. There are many options available.
You can use Flash media server , WebORB , FluorinFX and many others.
For WebORB you can find setup and examples here http://www.themidnightcoders.com/
For FluorinFX you can go here http://www.fluorinefx.com/
For FlashMedia server you can visit adobe site.
all the best