Just a slight clarification.
It looked to me as though the camera person moved himself in front of the muzzle for the actual sweep.
Nonetheless, I would like to think I would have opened the bolt, and secured the rifle before bending down to inspect the damage. And, if not secured the rifle, at least point the muzzle skyward on the other side.
Of course, we don't really get a look at the surrounding area in the vid. Maybe the way he pointed the muzzle was ordinarily the safest direction. For example, maybe there is someone's house in the other directions.
I can't criticize the instructor for not thinking forward that the camera man would cross the muzzle. I can see where it would have been thoughtful to foresee it; but I can't fault him for being absorbed just enough in the phonebook to not foresee it. Perhaps this is the real lesson here--secure the weapon first--always--then inspect the target, experiment, etc.
In the end, lets remember that the 4 Rules are layers of safety. Just exactly so that if one rule is violated, there are other layers to still prevent tragedy. No tragedy occurred, unless you were an advertiser in that phone book.