Delivery of streaming media to individual users is very successful, and the e-commerce models for this are well established, based on a one-to-one relationship between the purchaser and the content provider. However, as the demand for a particular product goes up, it is possible to exceed the processing limit of the content provider. The use of multicast distribution technology can lower the processing needs of the content provider and the bandwidth needs of the network operator. However, it requires the introduction of security features (to prevent theft by non-purchasers) and distributed accounting features (to collect revenue from the multiple purchasers). We identify the parties that participate in a multicast session, either before the session or during it. We then discuss the communications paths and security requirements that exist among and within these parties, for the support of this secure, accountable multicasting. We present an enhanced multicasting architecture, which enables the necessary security and accounting features, while keeping the additional load on the routers at a minimum. We then extend the architecture to facilitate deployment of multicast in parts of the network where no "native" multicast support is available.