There is only one file type that uses the .WMDB extension:
Windows Media Database File
Library of media files located by Microsoft Windows Media Player; contains a list of references to audio and video files located by Windows Media Player after scanning the hard disk for media files; typically named "CurrentDatabase_###.wmdb."
The WMDB file is referenced by Windows Media Player, but is not meant to be opened manually. WMDB files are used by Windows Media Player 9 and later.
|Microsoft Windows Media Player||Bundled|
Updated: July 28, 2014