You may want to ask this in the networking forum as well, but really all your doing is capturing video and sound (APIs like DirectX, etc. have support for this), sending the data (I'm assuming in some compressed and probably encrypted format), and then decrypting, uncompressing, and playing on the other end. The capturing and playing of the video is completely seperate from the net code. And having 5 peers, 50 peers, 500 peers is the exact same as having one. Your just using more sockets/sending to more IPs.

Theres a large number of samples on capturing video, some can be found here (I'm assuming your dealing with windows and C++, otherwise there are still quite a few using linux and/or other languages. Just search on google.):
Video

And there are tons of networking tutorials. For example:
Network

I haven't found any tutorials showing exactly what you want, but seperating out the parts you should be able to get some information prior to starting on it. Then again maybe someone else knows of some specific examples.