Yes, it's documented http://support.microsoft.com/kb/934371 although I
suspect the mms information was not well known until WMP11 came out,
and even then the docs didn't *seem* to mention it at the time.

The WM services FAQ details this better in a table : "What protocols
can I use to stream to Windows Media Player?"
http://www.microsoft.com/windows/windowsmedia/forpros/server/faq.aspx#2_1
and see the subsequent answer about "Why can't Windows Media Player
stream content from my server by using MMS?"

In general you should ensure your server is using Port 80 HTTP
streaming protocol in addition to the RTSP protocol, so that people in
restrictive firewall situations will normally still be able to receive
your content.

If you're running IIS or another web server on that Server 2008 box,
then you'll have to bind it (or WMS) to a different IP address -
whether that's a secondary IP address on the same network adapter, or
on a second public network adapter (card) on the server.

HTH
Cheers - Neil
------------------------------------------------
Digital Media MVP : 2004-2008
http://mvp.support.microsoft.com/mvpfaqs