i'm no flash expert but i don't think that macromedia flash is able to make socket connects, or open udp or tcp sockets. So you can't realize a flash streamer client cause you can't create a p2p network with it. No one can connect to the flash client. It's no P2P streaming!
If flash is able to do this it's interresting to hear, but i think no
Maybe it's possible with some perl scripts in the background and flash for the GUI but that will be slow cause it needs much cpu time on server (especially free hoster don't allow such scripts).