Video-on-demand (VoD) is increasingly popular with Internet users. It gives users greater choice and more control than live streaming or file downloading. Systems such as MSN Video and YouTube deliver content at low bitrates. This may suit short clips, but great films and 5-minute bloopers are as different as symphonies and jingles. For cinema, poor quality and high jitter are less acceptable. Combining user control with high bitrate is compelling, but technically challenging. VoD is expensive due to the load it places on video source servers. Many researchers have proposed using peer-to-peer (P2P) techniques to shift load from sources to peers (peerassistance), yet none have implemented and deployed a system with the first purpose of openly and systematically evaluating this approach. To fill this void, we have built and deployed GridCast1 . GridCast doubles the bitrates of current popular internet VoD systems, provides a full set of VCR2 operations, and employs peer-assistance ...