Canon 5D mirror and shutter in slow motion

Look at that mirror bounce around! This video shows why shooting in Mirror Up mode is a good idea.

Also, once the mirror is up, you can see the gap in the shutter as it moves downward. The leading side of the gap is the first (front) curtain, the trailing side is the second (rear) curtain. The sensor gathers its light as the gap passes over it. This is the exposure. The faster the shot (at a given ISO), the narrower this gap is. For best results, have a lens attached.