I have had an issue working on a website, where flash will not show up when the user is on the secure (HTTPS) side of the site. I found a solution, however, not by searching for it, just by trying different things, and it seems to work. All of the http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=7,0,19,0 needs to be changed to https://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=7,0,19,0, and all of the movie values and source values need to be directed to the absolute URL as in http://www.yourdomain.com/yourflashfile.swf, rather than a relative link such as yourflash.swf.

This works for all https situations in both IE7 and Firefox, and will avoid the”Big White Square” syndrome meaning Movie Not Loaded.