2-way webinars with video & audio

I want to do a collaborative pro-d session with 2-way, full screen, video & audio so that the other school can see us and we can see them. I don't need 'white board' or chat room. I want the 2 (possibly 3 groups) in different locations in the Canada and the US to be able to see each other and talk to each other in real time and have the video fill the screen. How do I pull that off? Any ideas?