In video-on-demand (VOD) system, efficient video delivery scheme can largely increase system service ability by reducing the resource requirement. Most existing schemes are not suited for the instance that the characteristic of the workload changing greatly with time. A workload adaptive scheme is proposed in the paper. It absorbs the outstanding thoughts from two efficient schemes: fast broadcasting and patching scheme. The scheme allocates adaptively the number of channels according to request rate to minimize the required bandwidth. We show how to seamlessly perform the transition of changing the number of channels while guaranteeing the clients currently viewing a video will not experience any disruption. The scheme can provide zero-delay video-on-demand (VOD) service. Simulation results show that the scheme adapts nicely to the changing request rate and improves the performance of VOD service significantly in terms of total server bandwidth requirement.