When Apple decided that users shouldn’t know about a file system, they basically made it impossible to move a simple thing like an iMovie project around. Here is the workaround. You have to look for the iMovie Events and iMovie Projects directory and move the stuff in there. How wierd is that…see http://imovie.maccreate.com/2010/01/19/making-your-imovie-09-projects-transportable/
iMovie 09 doesn’t have a native way to bundle up a project so that you can send it to someone else or so that you can take it on the road with you. But that’s okay because the file structure of iMovie is pretty transparent, so it’s easy to take your files with you.
The key is iMovie’s organization. For each drive you have connected to iMovie, the program simply creates a number of folders to contain the Events and Projects. Whenever iMovie launches it scans all the available hard drives for these files. If it finds the right folders on a drive, those are loaded into iMovie. If a drive has none of these folders, iMovie just doesn’t do anything.
The key files you need are in the iMovie Events and iMovie Projects folders. If you want to take your whole iMovie library with you, simply copy both to a new drive (be sure they’re at the root, or highest level of the drive). If you want just a few of the Projects or Events, make folders with theseidentical names (they’re case sensitive) and drag just the Events and Projects you want into them.