Apple DVD Player requires an internal DVD drive
Apple DVD Player works with the internal factory-installed DVD drive but will not work with external DVD drives.
To view movies on a DVD-Video using Apple DVD Player (Mac OS 9) or DVD Player 3.x (Mac OS X) you must have an internal DVD drive. Licensing restrictions of the DVD decoding technology prevent its use with computers that do not come with an internal DVD drive.
Computers that come with an internal CD-ROM or CD-RW drive and are not able to read DVD discs are restricted from viewing movies on DVD-Video discs using Apple DVD player. A "-70012" alert may appear if you try to play a DVD movie disc with an external player.
Adding an external DVD drive allows a computer to use DVD-ROM discs, but the Apple DVD Player application is still restricted from playing DVD-Video discs.
See "DVD Player 3.0.1: Compatible Computers" for information on the computers compatible with DVD Player 3 for Mac OS X.