At present, Web portals offering streaming of stored video contents or live TV channels have become a rapidly emerging new Internet service. We investigate the traffic characteristics, performance and perceived quality of available IPTV services which use peer-to-peer (P2P) overlay networks, called P2PTV. We analyze gathered traces of a comprehensive measurement study to determine the structure of P2PTV applications and the employed protocol stack with its related message flows. Furthermore, we compare the quality of different peer-to-peer dissemination systems and illustrate drawbacks and weaknesses of the approach.