A hybrid HTTP/UDP delivery protocol provides significant improvements for delivery of video and other content over a network, such as an overlay. The approach is especially useful to address problems (e.g., slow startup times, rebuffering, and low bitrates) for HTTP-based streaming. In general, the protocol has two phases: an HTTP phase, and a UDP phase. In the HTTP phase, the client sends an HTTP GET request to a server. The GET request contains a transport header informing the server that the client would like to use UDP-based transfer over the protocol. The server may refuse this mode and continue in ordinary HTTP mode, or the server may respond by sending an empty response with header information informing the client how to make the connection to enter the UDP phase. In the UDP phase, the client initiates a connection and receives the originally-requested content over UDP.