In order to approach video-on-demand (VOD) service, we can allocate more bandwidth to broadcast a popular video more frequently to reduce viewers' waiting time. Using broadcasting scheme to support a popular video periodically, in order to guarantee a given waiting time, the harmonic broadcasting scheme needs the least bandwidth in the existing schemes. In this paper, we will show that using any broadcasting scheme, the minimum bandwidth requirement for the same waiting time is the same as the harmonic broadcasting scheme. Therefore, for a popular video, in order to approach near VOD service, the harmonic broadcasting scheme is an optimal broadcasting scheme that needs the least bandwidth for a given viewers' waiting time.
