Yeh, it actually is detecting the operating system... it's all bull crap. I told them to bugger off anyhow. I sent them a note about 6 months ago and they told me they would never support the mac...something about the digital rights managements.
Yep -- for some reason, Microsoft won't include the digital rights management in the Macintosh version of Windows Media Player.
It is bullcrap. All they'd have to do is remove the browser check and it would run just fine (possibly better) on our Macs. It's simply meant to keep other OSs out, which is silly.