Hard drive full of "other" Is iMovie the culprit?

Issue: Friend's macbook pro is full of "other". The hard-drive capacity is 319.21GB. Other accounts for 262 GBs.

The macbook is running OS X 10.7.5 Time machine settings are ok – no screenshot problems.

I ran omni disk sweeper and the biggest area taking space is movies at 170 GB. iMovie Events.localized accounts for 158GB.

My friend says that she has noticed when she imports videos from her flip video camera they are larger than the capacity of the video camera. i.e. the flip 4GB capacity but when she imports the footage it takes up much more space on the computer.

So my first guess is that the issue is related to iMovie. I’m wondering if there is an import setting that is off. Any thoughts?