Accelerometers. How it works is there is something like a 5 minute, constantly overwriting video file. Once the accelerometers detects an abrupt deceleration, i

Accelerometers. How it works is there is something like a 5 minute, constantly overwriting video file. Once the accelerometers detects an abrupt deceleration, it determines an accident occurred and marks the previous 5 minute segment of video as read-only.