In providing video-on-demand services in multicast environment, a broadcasting technique like skyscraper is very efficient for serving a very popular video in terms of resource requirement. However, a multicasting method like patching will achieve better performance if the video is not popular enough. Since there may not be a clear distinction between very popular and popular videos, an analytical model is developed in this paper to select an appropriate delivery scheme for the videos according to both the popularity of videos and the customer reneging behavior. The result shows that not only is the overall bandwidth of the system minimized, but a preset quality of service is also provided for each customer when using our proposed scheme.