Efficiency is essential for Video-on-Demand (VOD) to be successful. Conventional VOD servers are inefficient; they dedicate a disk stream for each client, quickly using up all available streams. However, several systems have been proposed that allow clients to share streams. We present a new system called stream tapping that allows a client to greedily ``tap'' data from any stream on the VOD server containing video data the client can use. This is accomplished through the use of a small buffer on the client set-top box and requires less than 20% of the disk bandwidth used by conventional systems for popular videos. We present a description and analysis of the stream tapping system as well as comparisons between it and other efficiency-improving systems.