We might be able to walk them though a simple disabling of Flash but if they don't have Silverlight installed, then all they will see is the "download" link.
the 'allow-access-from'-tag, has an optional secure attribute which defaults to true, If your policy file is on an HTTPS server and you want to allow SWF files on a non-HTTPS server to load data from the HTTPS server, you can set the attribute to false. We have users that are really, really non-technical (yeah, running XP and IE8 would be a good indication of that) so I want to make the whole process as uncomplicated as possible. To build upon this, you can solve it through changes in crossdomain-policy file.
Is there any way to have the player fall back to Windows Media Player without having to download the file? Is there a workaround or fix for the Flash 12 problem? (not sure what it is but it is definitely broken). If I disable the Abode Shockwave plugin, the player does work and I assume that it's using the SilverLight plugin because if I disable that plugin, I am prompted to download the MP3 file and Windows Media Player plays the file. I have an XP VM that I fired up for testing and sure enough, when running Flash 12 on IE8 on XP, the MediaElement player stopped working. I have gotten multiple reports from our XP users (too many of them!) that the player has stopped working (playing MP3's) on our website.