This paper introduces a hybrid server/P2P streaming system called BitTorrent-Assisted Streaming System (BASS) for large-scale Video-on-Demand (VoD) services. By distributing the load among P2P connections as well as maintaining active server connections, BASS can increase the system scalability while decreasing media playout wait times. To analyze the benefits of BASS, we examine torrent trace data collected in the first week of distribution for Fedora Core 3 and develop an empirical model of BitTorrent client performance. Based on this, we run tracebased simulations to evaluate BASS and show that it is more scalable than current unicast solutions and can greatly decrease the average waiting time before playback.