Excessive buffer requirement to handle continuous-media playbacks is an impediment to costeffective provisioning for on-line video retrieval. Given the skewed distribution of video popularity, it is expected that often there are concurrent playbacks of the same video file within a short time interval. This creates an opportunity to batch multiple requests and to service them with a single stream from the disk without violating the on-demand constraint. However, there is a need to keep data in memory between successive uses to do this. This leads to a buffer space trade-off between servicing a request in memory mode vs. servicing it in disk-mode. In this work, we develop a novel algorithm to minimize the buffer requirement to support a set of concurrent playbacks. One of the beauties of the proposed scheme is that it enables the server to dynamically adapt to the changing workload while minimizing the total buffer space requirement. Our algorithm makes a significant contribution in decr...