Content distribution networks (CDNs) are a popular service for the
dissemination of multimedia content over wide areas. The existance of a centralized administrative structure makes them attractive for the
commercial distribution of high quality content. By sharing resources,
service providers can implement their services more efficiently than a
single content provider who establishes a distribution structure himself. An efficient operation requires cost estimations that allow service providers to determine the dimensioning of their infrastructure and the placement of content in the system. In case of video streaming, distribution mechanisms that exploit multicast, segmented delivery and out-of-order delivery can be applied to merge streams and reduce resource consumption. Several applicable stream merging mechanisms exist in the literature and can be used. We examine three such mechanisms, namely patching, gleaning and prefix
caching in a hierarchically organized CDN. We show that a co-optimization of movie placement and stream merging mechanism has an undesirable effect on quality by delivering highly popular movies over longer distances than less popular ones. We explore and compare two approaches for overcoming this problem by qualifying the placement optimization with additional conditions. We find that in this case, straight-forward sorting is a good solution.