In order to retrieve any file from within any Flash (including motif) ad served by an external server, certain steps must be taken to meet the Flash Player’s security requirements. The web server that hosts the file being loaded into the ad must have a security document present at the root of the web server. You must create the file named “crossdomain.xml” to outline which domains are allowed to connect via Flash to that server, and place this file at the very root level of the web server. This was handy to learn because our clients couldn’t handle flash banners bigger than 40k without charging more. Here is a banner I created that loads another flash swf file into the main swf file. Click here for a detailed how-to on
loading external Flash SWFs into another hosted Flash SWF.