Media Player 8 extension for DVD play
Media Player 8 - DVD Play enables you to play DVD (MPEG2 + AC3) in Media Player 8 (Actually CyberLink PowerDVD 3.0).
More Info MS KB308012
Note it seems that setting this STRING value in the registry also can do the trick in WMP 6.4:
[HKEY_CURRENT_USER \Software \Microsoft \MediaPlayer \Player \Settings]
EnableDVDUI = “Yes”