This is a training video. The easiest way to tell is that after the perp is shot, the officer in front begins to re-holster his weapon, even though the perp is still holding a gun in his right hand. In a real shooting, the guns stay out until they *have* to be put back in their holsters.
Typically, a police officer will re-holster quickly when there hasn’t been any shooting, and another office has his gun on the perp. But if real bullets have been flying, the guns stay out.
Another cue is that only three bullets are discharged. If police shoot someone, they often intend that they stay shot.
The big technical question I would ask the officer behind the perp is “What were your aiming points?” This is a good thought problem, but not for an obvious reason that most people don’t think about shooting someone in the back. The real reason is the *other* officer in front. The bullets could have gone through the perp and hit the other officer.
Regarding your question on aiming points: Police are being taught that the old concept of “center mass” as an aiming point, be modified to “center OF mass.” It’s a subtle change, but it means that one shoots at the mass center of whatever is presented to him as a target. Front or back doesn’t really matter; if the shot isn’t taken, the perp’s threat becomes the act.
And, as always, police are not taught to shoot to kill or wound; they are trained to shoot in order to stop the threat. This implies that shooting continues until the threat is stopped. A perp on the ground with gun still in hand may still be a threat, depending on what the hand is doing.