Olympus has a feature called pre roll in the movie mode. In the pre roll mode it constantly records 2 seconds of video before you push the record button. Generally used for capturing that home run your kid gets. You push the record button after the event and it has already recorded 2 seconds.

She really liked using the feature during an electrical storm to catch lightening strikes. Just point the camera and when lightening strikes push record and you have it on video. Nice feature.