Application-level multicast overcomes the problems linked with IP-multicast and provides an effective mechanism to support media streaming. One key problem associated with this approach is the restriction on the content that can be distributed because the upstream capacity of the peers is utilized to forward content to other peers. As the upstream capacity of most peers is restricted, webcasting highbandwidth content is a continuing problem with traditional application-level multicasting techniques. Split and Merge Multicast provides a solution to this problem. This paper presents the results of a largescale field trial of the technology.