Quite simply his rifle has no ammo magazine in it so at most it could potentially have one round in the chamber, one shot and nothing else. The guy to his right is standing right in the path of the spent casing that would be ejected out and would likely be hit in the face. Also as another pointed out the rifleman is trying to peek around the corner looking for a threat but the cameraman is standing right there in the open without a care in the world as if having a camera makes you bulletproof.

If this was training footage then still begs why is the New York Post trying to pass it off as combat footage?