Video chat

This project is to develop a video chat room for an existing php/mysql site. I want a cost per user in terms of bandwith & storage space although no webcam capture has to be permanently stored. Users will be existing members so the video chat room only has to support a webcam capture in a 1 to 1 scenario Outline how you would do this and whether you have done it before. I don't want to use the Flash Communication Server.