VISTA experts! Why won't VISTA show me Any File (*.*) type by default?

In particular when I Open a file from WMP. It only shows me "Media Files (all types)" but laughably it omits the m4v files I just created. Can you help me make WMP and VISTA show me the m4v by default without me having to go down to the Media file drop down menu and manually select ANY FILE (*.*)? THANKs!!!