Why iMovie 10 doesn't move the original clips

Hi

In previous iMovie versions when importing video clips the clips moved (or copied) to a new folder location (usually the event). Now the originals stay in the same original folder and are copied by default into the new imovie library which fills-up the HD pretty quickly! I can understand the flow if I import directly from a camera/ phone but I have many hours of footage already on my HD and don't need them to be duplicated.

Cheers