dynamic update for post messaging

I recently created some flash banners for the web. The flash files required root click tag coding (_root.clickTag). They requested back up GIF files which i created in fireworks. The issue is the email i got back asking to "confirm the animated gif/jpeg will dynamically update for the post messaging?" does anyone know what this means?

Not sure either, except that perhaps they want to know if they can load a custom GIF into the SWF?