I had to move data from my iMac to my new MacBook Pro, and iMovie event and project clips were some of the data that needed moving.
I wasn’t running Time Machine on the iMac, so I just took the following steps.
Step 1
This is optional, but now is probably a good time to think about rejecting unwanted iMovie clips and moving them to the Trash in order to reduce the size of the files to be backed up.
Step 2
Prepare your backup device.
I used an external USB hard disk.
You could also transfer the files directly from the source Mac to the target over the network, but I found that moving files using an external drive was much, much faster.
Step 3
Locate the Movies folder in Finder.
The Movies folder can be found in your Mac user home folder (davidchin in my case).
There are two sub-folders within the Movies folder, called iMovie Events and iMovie Project.
You might want to go ahead and just take a quick look into what kind of files exist there.
Select both folders (using [command + click] on the folder names), and then just drag the folders to an external hard disk.
Step 3
Locate the Movies folder in the destination machine.
Drag the two iMovie folders to the Movies folder, and you’re done.
Conclusion
Launch iMovie 08 in the target Mac and confirm that the project and event clips appear.

{ 4 comments… read them below or add one }
Any advice for situations where individual iMovie files are larger than 4GB ? My external HD is FAT32 (max file size is 4GB).
Is there a way to split these large iMovie (.dv) files?
Hi David. If I’m moving them to an external drive and then totally cleaning my computer hard drive and starting over, do I just wait until the new operating system is installed and then put them back in place?
Thanks, Greg
Yes Greg, that’s what I’d do.
I want to make a copy of an iMovie 08 project onto an external USB hard drive to send to stock footage company. Pretty large project(2 hrs +). How to do this? Thanks