i had issues with that a while back. my solution was to actually create the video plugin onclick. when the hotspot is clicked addplugin(videofile); set(plugin[videofile].url,videofile.flv); add each variable that you need. then onclick to close removeplugin(videofile); that removes it from the stage. when you click to open again it should be rebuilt and work. this solution also makes it so the video file is not downloaded when the pano is loading it will not start streaming until it is created.
there might be a better way to do this but that works for me.