style.overflow= "visible" causing refresh

[flycast]

I am using style.overflow= "visible" to make an expanding flash movie on a web page. I have a div that contains the movie. I use style.overflow= "hidden" as default and then change it to style.overflow= "visible" when it is clicked. The challenge is that when the state changes the flash movie inside the div is refreshed and starts over - but only in Firefox. It works fine in IE. When you click on it a second time it works properly.

Any ideas on why the div and flash animation is refreshing when that value is changed and how can I avoid this?