Just came across this, had a similar need.
Suggest the following changes.
1: Make a "smart album" in the iPhoto with the condition "Photo is Movie".
2: Select a movie in the smart album created at step 1.
3: Press ⌘-a (select all)
Export in the
5: In the Export Dialog, choose
(optionally, you can choose subfolder
:Event Name. This will put the movies in folders based on the event name)
This will export all your movies. Now you simply need to delete the movies out of iPhoto.
I have not found a way to do this in an efficient manner since Apple in their wisdom did not allow you to use delete on movie objects in a smart folder (you can for pictures.. odd, bug I find a lot of these inconsistencies in Apple products), instead you must find the actual file in the event folder and delete from there. You can use the smart folder to take you to a given movie in the smart folders source event by bringing up the context selection menu and choose show event.