The player supports AVI, MPEG4, WMV, QuickTime, MPEG2, ASF video files that are already on your computer. This means no streaming content unless you have some software that captures streams and saves them locally (which is questionably legal, but since you'd be using it like a dvr...) and also some software to convert the flash video files to something the sansa can handle.

I found this handy tutorial for you: http://gleez.com/board/general/general-discussion/how-put-video-sansa-fuze