Panorama Event not firing always "onmouseout"

Hello I have a big problem. I made a hero selection screen. There are all heroes with portraits and if you move over you see the animated video portrait of vanilla dota.

The problem is onmouseout is not firing always. If you move quickly over all portraits they will stay at video animation.

I made a video to show you the problem: Video Do you have an idea how I can fix this?

What I just do is

        heromovie.SetPanelEvent("onmouseout", function() { 
   = 'collapse';
   = 'visible';