Terminal. If you are using video editing software like
Final Cut Pro,
iMovie or
Adobe Premiere, you can open the mpeg file and check it's frame rate. If it's 25 frames per second it's PAL, and if it's 29,97 then it's NTSC.
Wax. Flip4Mac WMV 2.1 is pretty good software. It allows you to view WMV's using the Quicktime player.
Check
http://mac.softpedia.com for more info. Some stuff is free and some you'll have to pay for.