The Slow Mo Guys do just what their name implies - record slow motion videos. In a new episode they use a Phantom Flex to capture the Canon 7D's mirror box and shutter mechanism being triggered at a variety of shutter speeds (1/4000s, 1/8000s, etc). The footage itself was recorded at 10,000fps, and the result is a look at a shutter in action - something that would otherwise be nearly invisible to the naked eye.