When you do get a Mac for testing be sure to test with Safari not IE as Safari is the default browser and IE is no longer even made for the Mac.
With the little bit of testing I did back when she still had some WMV files WMP got sent the login page so I just assumed that WMP was unable to be authorized as it is a separate application trying to access the members area.
There still is one issue with mpegs and Safari when using Strongbox. If you try to right mouse click and save the mpeg to your hard drive before playing it for a few seconds first the login page will get downloaded instead. I'm guessing that it is an authorization issue. This doesn't happen using Mozilla, but most Mac uses are using Safari these days.
I haven't really done any testing using IE as it is a dead browser on the Mac.
If you need anything Mac related just ask.
