A client device presents streaming media and includes a stream manager for controlling streams, a request accelerator for making network requests for content, a source component coupled to the stream manager and the request accelerator for determining which requests to make, a network connection, and a media player. A process for rate estimation is provided that will react quickly to reception rate changes. The rate estimator can use an adaptive windowed average and take into account the video buffer level and the change in video buffer level in a way so to guarantee that the rate adjusts fast enough if there is a need, while keeping the windowing width large (and thus the measurement variance) large. A guarantee might be that when a rate drop or rise happens, the estimator adjusts its estimate within a time proportional to a buffer drain rate or buffer fill level.