There is no separate iMovie trash. There is only the Mac's trash.
You want to use iMovie to MOVE, rather than COPY the Events to an external drive. Instructions are here. Do not move in the Finder. This will break your projects.
Thanks for the information! I actually have moved the events to the external hard drive which worked just fine.
My inquiry now is how do I free up space on my Mac's hard drive? After moving all of my projects off, I began the clean up by moving a 14gig event into the Mac's trash. The trash icon recognized the event and showed there was 14 gigs ready to be disposed. Upon emptying the trash, I should've gained 14gigs back but I didn't get the space. I currently have 115 gigs free but it should be at 129........I have installed OmniDisk Sweeper and it can't seem to find the files.....Should I run verify disk again to see if this works or are there any other suggestions? I definitely would like to get that space back so I can work on future projects.
In your case, there is no way to get the space back.
One thing that could have happened...
If the 14GB file was on an external drive, here is what happens when you delete it. The 14GB file shows up in trash. The trash contains a link to the 14GB file on the external drive. The 14GB file is not deleted from the external drive, but the directory entry is deleted so it does not show up in the FInder. So if you want to restore the file later from trash, it will restore the directory entry. You can see the file, and it is as if it were never deleted (which it wasn't). However, when you empty the trash, the physical 14GB file is deleted. You get the space back, but if it started on an external drive, you get the space back on the external drive.
That is one scenario that would explain what you are seeing. I am sure there are others.
If the 14GB file was originally on the internal drive, then the same thing happens. When you move it to trash, the directory entry is deleted, but remains available in the trash. When you empty the trash, you should see overall space go up by 14 GB.
There is another source of disk usage. Your Mac has a certain amount of memory. In my case, I have 16GB of memory. When I need more than 16GB, because I am running multiple applications at the same time, some of the memory is "swapped out" to the internal hard disk. Over time, you can get multiple swap files, and they get bigger and bigger. YOu can see this in the Activity Monitor. I have a free app called MemoryStick which shows the swap files more explicitly. These can get large and take up a lot of space and make your Mac sluggish. The easy cure is to restart your computer. That may get you back some space as well.
I have read this thread with interest, because I have the same problem - deleting clips, events and projects in iMovie 11 does not free up as much disc space as I expected. However, I have just discovered that my problem is not actually with iMovie, it is with iDVD.
I imported 6 x 1 hour mini DV tapes into iMovie 11. I created an event and a project for each one in turn. I then shared each project using iDVD. After making two copies of each DVD, I exited iDVD using the 'delete project' option. Following this I deleted the events and projects in iMovie and emptied the main trash.
iMovie 11 has behaved fine. However, using a disc usage utility I discovered that in ~/documents/ there were all the iDVD project files. I have now deleted these and freed up nearly 60 GB of disc space.