What happens to image clips? Can they be migrated with the database, or do they get left behind?
good question.
Images are stored as normal files, sorted into subdirectories by date. You can see that if you go to the File menu and choose "Browse Clip Image Directory".
The text notes associated with an image are stored in the database as normal, as well as the path to the image file.
So if you merged clips the images would migrate over if their location didn't change. If you merged clips from another computer, you'd have to move over the image files as well, possibly changing the paths to the image files if they have changed.
If an image can no longer be found (for example if user deletes it) then it will still be listed in the clip list database, it's just the image won't be available.