Mac users usually very wisely ignor M$'s WMV & WMA formats. Ignore files that ask for licencing or want you to connect to the net. These are diallers, marketers & porn sites. See
this
Also be aware of
autogenerated spam results &
What you should know about WMA Files which also applies to WMV files.
A hint to read this:
Movie download issues
A trusty mac video player is VLC:
http://www.videolan.org/vlc/ (choose nearest mirror site)
Whilst QuickTime player can be used, it helps if you have all the necessary 3rd party plug-ins which aren't always easy to get. And QT player cannot play WMV! VLC will be more reliable for previewing anyway. And it can play WMV files so long as they don't require licencing or have DRM.