Peer-to-peer based streaming has been a promising solution for large-scale video broadcasting over the Internet. In a peer-to-peer video streaming framework, peers cooperate with each other for content distribution, so that the burden of the central server is greatly alleviated. Moreover, the peer-to-peer overlay is highly scalable to support a very large number of users. However, to support video streaming service, some strict performance issues need to be addressed, e.g., reliability, resilience and robustness to network dynamics. In this paper, we investigate several goals that a peer overlay should achieve in order to support goodquality video streaming. We then describe our work on organizing peers into such a robust and resilient framework. We have implemented a fully functional video broadcasting system based on the proposed peer-to-peer infrastructure. The prototype system has been successfully deployed and tested upon Planet-lab with encouraging experimental results.