We're all adults here. We know to always leave the car in gear and put the parking brake on. But mistakes happen. So I'm not here to ridicule our mechanic friend, but to praise him, because this has to be the greatest runaway car save I've ever seen.
Just watching the video doesn't do our hapless grease monkey's harrowing act justice. So let's break it down.
First, there's the "Oh, shit!" moment. Then the realization that the driver's side door is about to be smashed into the side of the garage. He slides across the floor to save it, slamming the door milliseconds before the impact. He then hops in, Dukes of Hazard-style, seems to turn the wheel to avoid crunching the side of the Hyundai parked outside, then crouches down, possibly applying the brake with his hands to bring the Mustang to a halt.
A hero is born. Now he just needs to learn how to use the damn park brake.