With 5 or 6 through-and-through gunshot wounds to the chest, the death I would expect to see would be utter silence. Almost instant unconsciousness and cardiac arrest would be the most likely outcome from such massive damage. What people often don't realize about gunshot wounds is that as a bullet travels through flesh, it creates a wound channel much wider than the bullet itself due to cavitation (scroll down). And if the bullet is a hollow point, it also flattens out and becomes much wider, making an even larger wound channel.
2. Cavitation: When a high-energy projectile travels through the relatively liquid human body, it forms a cavity along the track of the
bullet. In actuality, there is both a permanent and a temporary cavity
formed. As a bullet moves through the tissues the energy of the bullet
causes a temporary radial stretching, forming a cavity that soon
closes as the energy is dissipated. However, within the central
portion of the projectile path there will be enough tissue damage to
cause a permanent cavity. For low-velocity weapons, such as knives,
there’s little difference between the permanent and temporary cavity.
As the energy of the projectile increases, however, the size of the
temporary cavity increases accordingly. In essence, a considerable
amount of damage is done by the formation of the temporary cavity.
This is why high-velocity/high-energy weapons can cause so much more
3. Shock wave: This is a rapid change in pressure, temperature or density secondary to the projectile. In high-energy, high-velocity
weapons, shock waves can sometimes approach 200 atmospheres of
pressure. The shock wave generated by the bullet usually lasts only a
few microseconds. However, the result can be extremely damaging.
Several factors related to the bullet affect the subsequent injury.
One of these is the bullet’s profile. The profile is the size and
shape of the bullet as it contacts the human body. The larger the
profile, the greater will be the rate of subsequent energy exchange.
Most bullets will rotate or tumble somewhat on their axis during
travel. Yaw often takes the bullet slightly off of its course. This
can occur during travel through the air or as the bullet strikes the
body. Short, high-velocity bullets tend to yaw and rotate more
severely when they strike human tissue. Rifles contain grooves within
the barrel (rifling) that imparts a spin on the projectile that serves
to minimize yaw and tumble. Thus, the greater the yaw or tumble of a
projectile, the more rapid the subsequent delivery of kinetic energy
and resultant damage. The shape of the bullet also affects the
subsequent energy delivery. Some bullets are designed to expand when
they strike an object, causing more injury.
The point of the above is that the finger-sized entrance wounds you see would become much larger internally, so the odds of all those bullets not hitting something immediately lethal is vanishingly small. With that much damage, I would expect almost instant unconsciousness from massive blood loss.
Yes, it's remotely possible all those bullets miraculously missed his heart, aorta, and assorted other major vessels, leading to a slower, more dramatic death. For purposes of making a movie, that's certainly a more dramatic ending and the one they chose for that reason. After all, bodies lying face down on the pavement are pretty boring.
As for the comment you asked about, that's mostly rubbish. What you see in the video that could be realistic is the agonal respirations, but the comment didn't even mention that. The bit about organs shutting down, flashbacks, and nerve endings firing is a bunch of stuff from the commenter's imagination.
What's actually going to happen is he will be bleeding massively in the chest. The physical damage and blood loss will lead to cardiac tamponade, hemopneumothorax, shock, unconsciousness, perhaps some agonal respirations, perhaps a brief seizure, and cardiac arrest.
The commenter's opinion that it's a highly realistic portrayal of death is unfounded. It is dramatized.