While posting panoramic videos for Sziget 360 (http://sziget360.com/panoramavideo), I found out that when using Firefox the flashplayer would become extremely sluggish playing back panoramic video; scrolling the html page would be nearly impossible, and in non-fullscreen mode the framerate frequently became so low that Firefox suggested that the flashplayer should be closed. It turned out that by setting the wmode parameter to "window" (instead of the default "direct"), the video shows smoothly (like it did on chrome on the same machine).
So I added the following code to set the wmode param for Firefox: