When you add any media file—a movie, a photo, a song—to your iDVD project, the project contains a reference to the location of the file on your hard disk, not the actual movie or picture file. As a result, if you delete or move the file from its original location, your iDVD project can no longer access it. Therefore, don’t delete or move files you add to your iDVD project until after you have burned the project to a DVD or made a disc image of it. Or, if you are not ready to burn your project to DVD but need to move it to another computer, you can create an archive of your project that contains copies of all the media files used in the project. You can then move the archived project file to another computer or hard disk to continue working on it.
Viewing all the files in a project
Archiving an iDVD project to back it up or transfer it to another computer