I had read some blogs posts about the new smooth streaming capabilities for IIS 7.0, but I never actually experienced them myself. IIS Smooth Streaming is a technology that works with Silverlight in delivering a smooth video playback experience from Microsoft Internet Information Server in circumstances with varying network bandwidth.
It is really easy to try it out for yourself via http://www.iis.net/media/experiencesmoothstreaming
You get some controls to play with to artificially throttle the bandwidth available to Silverlight for downloading the video stream. If you throttle it down you can see how the stream smoothly switches to a lower bitrate version of the video without too much glitches in the playback experience. If you give Silverlight full bandwidth again, the bitrate gradually climbs up till you get real HD quality again (assuming your maximum bandwidth allows for that). A picture says more than a thousand words:
It also works with the Linux variant of Silverlight called Moonlight. Check out Miguel de Icaza’s blog for that.