Most DVD playback players, like InterVideo WinDVD have snapshot functions built in. WinDVD is usually bundled with a PC. Pause the video where you want it, and snapshot it.
I have the WinDVD...How do I snapshot?
It's actually windows media player
MediaPlayer won't do it on it's own. You would need a program like SnagIt to do a screen capture, but the resolution isn't great. The best way is find someone who has WinDVD on their computer if you don't. And this is all assuming this is really a DVD movie, and not an MPEG file on a DVD. Big difference.