WMP, not WMV, is no longer supported or supplied by M$. A trip to their site will put you in a position to download a program called Flip4Mac which contains a bunch of codecs for QuickTime in a neat installer.
I use it regularly without too much of a problem and it will play M$ streaming video that the M$ WMP for Mac would not.
WMP for Mac has always sucked and it was always free.
There is also a plug in for Safari that should indicate that the M$ stream can be read.
What is the URL of the "listening party" site?
As a tyro iMac G3 user some 3-4 years ago i tried the ''free'' download of the extant WMV version 7 for mac. It did not produce anything of use except a beautiful choice of onscreen ''skins''. There was audio, no video. A call to tech. supt. at microslop offered the answer, i could (since this was going to take some time to solve) give them my credit card numbers and they would (with no guarantees) talk me through it for about $30 per half hour. [This after a microsoft AND mac-owning friend and i had deleted and re installed the software.] (several attempts) That didn't seem like a good bargain to me. i deleted it for a final time and didn't look back.
Fast forward to present day. ''Old'' iMac OS 9.2 now replaced by OS X 10.2.8 for a couple of years and having a slow day prompted me to try out WMV version 9 (for mac). It worked beautifully but with a catch. Since microslop wasn't going to be using version 9 (for mac) anymore there would be no tech. supt. available. ''Even better'', sez I! they won't need my credit card numbers to get it to work. Maybe that is why it is offered for free now. Old Henry Ford used to boast he could give his cars away and still make millions on repair parts sales. Mostly WMV 9 will still will download and play video off the internet and from email sent to me. So far the one exception is a CMT ''listening party'' site. They insist on their page: (and this is a direct quote)
''Q. I have a Mac running OS X, but I have a Pre- Windows Media 9 Player. The Video window shows blank. What's wrong?
A. You need to get the Windows Media Player 9 version from Microsoft. Then you will be able to view the videos.
Now, since my onscreen error window message says: unable to play invalid format, Can i safely assume it will stream in an as-yet unknown format that tech. supt.microslop will want to help me receive for $30 per half hour ?