That's excellent penetration at that range.  Far beyond the intended range. 
His pattern was much wider than results we had with the shotgun used in that test video above.   I think that shotgun was my 870 Police Trade In gun I snagged for crazy cheap. 

Beyond the normal pattern variations from different shotguns; temperature, humidity and altitude can influence patterns.  Cold weather, in particular, is known for opening patterns.

Though not specifically about buckshot, the following link presents some of the environmental factors that can alter shot patterns:
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"Air temperature changes from summer to winter can cause air density variations up to 25%, with a similar change in your shot pattern. That means tighter patterns in hot and warm weather and more open patterns in cold and dry weather."

 http://www.shotgunlife.com/shotguns/guns/busting-the-big-myth-about-shotgun-chokes.html

Never understood the "00 buck only" doctrine.

The use of 00 buckshot as "standard" comes from a 19th century USPS contract, not from testing.  I think a #1 load has better potential for defensive use.

Ah yes...
So...
At 50 yards, it's still moving at 1031 FPS... So much like most handgun rounds, and it's still 9 pellets at about .32 or .33 caliber. 
So, yeah... Very much.

The full power FliteControl 00B is PFC154.  9 pellets at a rated 1325 fps.  Don't know what it does in fps from my 22" IC, but, it should hit pretty hard at 50 yards.  Certainly patterns well at that distance. Bought 10 five round boxes back in the summer.  Cleaned out the store.  Would have bought more, if I could.

Also helped by the design of the model 37 which screwed the barrel into the receiver instead of the system adopted by Remington. 

I'm sorry but I have owned and seen Model 37's manufactured since 1963 and they have had threaded barrels which screw into the receiver.  Deerslayer or not.   

Consider Rifled Slugs in the 1970's:

Twelve gauge rifled slugs were originally smaller than bore diameter, with most running to .690 - .695 inches. It was only in the late in the 1970s  that Winchester increased the diameter of its rifled slug ammo to the nominal 12 gauge bore diameter. Federal followed soon after. Remington held out, making undersized slugs into the 1980s.  So, these sub-diameter rifled slugs were the norm from their mid-1930s introduction well into the 1970s and were considered minimally accurate only to 60 or so yards.  Indeed, the Ithaca Deer Slayer, introduced in 1951, was produced with a reduced bore diameter to match the diameter of rifled slugs at the time.  The Deerslayer, alone among contemporary deer shotguns, delivered usable 100 yard accuracy with the heavy undersized soft lead thimbles.

Somewhere in the '70s perhaps even a bit earlier, the Brenneke slugs were introduced in the US.  That design was more accurate in the smooth bore slug barrels of the era that any of the Foster type slugs.  I think I was using them by the early '80s, if not earlier, when I had a need to hunt in heavy cover and needed a bit more range or penetration that the crappy buckshot of the day provided.  There were places where we simply could not use rifles.  Still true on some type of hunts, especially when the deer are driven ahead of a pack of Walker hounds, running in deep piney woods. 

I think I may have a round or two of the early Brenneke slugs that I retained as a keepsake.  I believe that the screwed on wad on the back they used at the time was actually felt.  But the design, with its six larger fins and weight forward emphasis, simply worked.  They were not cheap, though.

I don't know if the Brenneke slugs got any traction in law enforcement circles.  They sure did with serious hunters limited to shotguns for whatever reason.

I don't know if the Brenneke slugs got any traction in law enforcement circles.

Brenneke is certainly trying to penetrate the law enforcement market these days - pun intended!

See:
http://www.brennekeusa.com/cms/fileadmin/BrennekeUSA/Law_enforcement/user_upload/Dokumente/Brenneke_Maximum_Barrier_Penetration_Slug_Information.pdf

Update:

I don't think I agree with the conclusion(s) drawn by the producers of that video.  A single officer responding to an armed robbery of a jewelry store and able to park on the street near the scene of the crime needs to bring all the firepower he can muster to the engagement.  He had no idea what he would be facing.

1) A store owner and maybe a witness or two in the aftermath of the robbery.  No firearm needed at that time.

2) A robbery in progress with one, or more, armed assailants.  A firearm is definitely needed and the shotgun's capability could prove essential in either convincing the criminal(s) to surrender peacefully or neutralizing the threat(s). 

3) A robbery in progress with one or more armed assailants attempting to flee the scene either on foot or in a vehicle.  A firearm is probably needed and definitely would be needed in the event of close pursuit with the possibility of an armed confrontation at some point.  Again, the shotgun's capability could prove decisive as it gives more options than the sidearm.

4) A robbery in progress with the criminal(s) opening fire on the responding officer on a downtown city sidewalk in broad daylight during business hours.  A firearm is definitely needed and with the officer and innocent bystanders already coming under fire from the criminal(s) the shotgun is the most decisive fight stopper available to the responding officer. 

The responding officer knows that one round has already been fired by the criminal and may have already taken an innocent life somewhere behind him.  At that point he has the obligation to neutralize the threat to himself and all bystanders and only a split second to make the decision to fire.  The range to the criminal in the video appears to be roughly twenty five yards - perhaps a bit more.  At that range a center mass hit by a load of 12 gauge buckshot is usually decisive and frequently fatal as it appears to have been in the video.  Threat neutralized with little to no chance of overpenetration endangering anyone beyond the target.  Three bystanders were hit in the video which means one third of a 2 3/4" load of #00 buckshot missed the target at roughly twenty five yards.  How many rounds from the officer's service revolver would have been necessary to stop the assailant and if it was more than one how many rounds would the assailant fire in response?  Would any of those rounds have hit innocent bystanders? How many rounds from the officer's service revolver would have missed the target at the same distance under the stress of responding to an armed assailant? Would any of those rounds have hit innocent bystanders?  Would any rounds that hit the assailant overpenetrate the target and endanger innocent bystanders? 

At this point I'm calling it tactically sound to arm yourself with the shotgun in those circumstances - especially in the absence of any other  weapon superior to the service revolver.  I also find it tactically sound to use that shotgun to end the clear and present danger of gunfire on a crowded city street.  It is regrettable that innocent bystanders were injured in the exchange of gunfire but given the circumstances it seems to me that the officer made the best choice available to him.   

couple of points from my office.

we've pretty much stopped using shotguns now.  When we did still carry them I only issued slug rounds.   Biggest reason is that even using the buffered, special tight group rounds,  your still firing 9 or 11 pellets and you are absolutely responsible for every single pellet.  I did not want that liability risk anymore.  Plus with slugs and good sights,  we were confident of making a solid hit even at extended ranges.

Now,  the shotguns sit in the armory locker and we issue, train with and carry a semi auto only M4 with red/green dot optics.  We train from 100 yards and in.

Doug

I agree that a slug is probably the superior choice of ammunition for most line of duty police encounters.  Still, you have to "run whatcha' brung" which speaks to Kaso's point about knowing how your service weapon patterns with the issued ammunition. 

A lot has been learned since that video was produced and police weapons and tactics have changed considerably - as they should.  It is a dynamic environment and what works one day may be unworkable the next.  The video seems more an acknowledgement of the legal liability aspect of policing rather than a lesson in effective gunfight tactics.

What better source to turn to than the black powder crowd for lead ball ballistics? 

http://www.ctmuzzleloaders.com/ctml_experiments/rbballistics/web_apps/rb_ballistics.html

Just a note:

The program is set up for unalloyed lead balls. 

For the most accurate results, measure and weigh the pellets.  The diameter, (to the nearest hundreth), and the actual pellet weight can then be entered into the appropriate boxes. 

Also remember that industry instrumental velocity test results are taken from 30 inch barrels* at at a distance of 3 feet.
*12 gauge