We post this video reluctantly, and in part only to show what not to do as a pilot, though this one kind of goes without saying, at least we hope so!
In it, a front-seat passenger in the 1946 J-3 Cub unbuckles and proceeds to reach out of the Cub’s open side door and hand-prop the stopped engine, a 65 hp Continental. He’s tethered by his belt to something inside the plane, though if he weighs 170 pounds (let’s say) and if he falls a few feet, the dynamic load would be in the area of 300 pounds if it’s a static rope and somewhat less if it’s a dynamic (stretchy) rope, like rock climbers use. The belt’s strength? We’re guessing less than that, but it’d be close. And there appears to be no other safety backup. Creating the video was a monumentally bad idea, because a fall from what appears to be more than a thousand feet wouldn’t turn out happily. The hand-propping risk isn’t zero either. Then if one wants to get into the potential FAA fallout…we’ll let you use your imagination on that one.