"Digital Copy" is the term they give to a bonus disc that comes with said edition of the film. On that disc is a file much like a divx avi or ipod-formatted mp4 that acts as your personal digital copy to use on your computer or portable media player.
... Only problem is that they look pretty crappy and with a little know-how you could make your own "digital copy" from said DVD and it would look/sound much better, not to mention specs would be catered to your specific needs.
It's sad and unfortunate that this unnecessary practice is now making its way into Australia with Fox and Disney films. Mine will go straight in the bin. Blech.