http://www.cryer.co.uk/filetypes/m/ says it's a descent 2 movie archive.
http://www.descent2.com/ddn/kb/files/ says the same. However, it doesn't offer an extract program anymore, because of copyright reasons with InterPlay.

Better contact the makers of descent 2 for more information, I should say. Or find your way around the hacking scene. It has nothing to do with MS Office, that's for sure.

Kees