I’m putting together a video player and I wanted to test the scrubber (the little button you use to drag the playback) was working.  More importantly I wanted to test it couldn’t be dragged further than the video had downloaded.  So I uploaded an flv to my site and tested the player.  This was fine the first time and then the stand alone player cached the flv, so I couldn’t test it anymore.  A quick google and I found this really handy tip.