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

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