I knew the 70D focuses fast. I wanted to see how fast. So I panned around the room with the 70-200mm and let it find focus on it's own. The results are astounding. Of course, most want to focus by hand or have the luxury of a focus puller. In the situations I film in it's a real blessing to have a camera which can focus this fast.
And to get it to stop focusing you can always just tap the screen to turn off Auto Focus.