The "D" in DSLR does not stand for dark magic. In fact, that snap of the shutter you hear when taking a picture is a wonderful symphony of mechanical engineering at work, and it happens so fast that you can't really enjoy it all with the naked eye. Luckily, the Slow Mo Guys have painstakingly chronicled what's happening with the mechanical shutter of a Canon 7D using a very fast (and expensive) Phantom Flex camera, recording various shutter speeds at a mind-boggling 10,000 frames per second.
The result shows what happens when you click that shutter button, including the viewfinder mirror lifting while the rolling shutter exposes a portion of the sensor. Slowed down you can see the obvious, though normally invisible differences in the various speeds. Slow Mo Guy Gavin Free also shows how the rolling shutter effect can end up creating bizarre and often unwanted effects in both stills and video, something that is thankfully not apparent in this video of melons being detonated, which was filmed using a different shutter technology.