There was a young girl killed in Maryland back in the mid to late 60's by a stray 22 from almost a mile away. Bad luck to be sure, it hit her behind the ear. But it was from a man hunting squirrels with a 22 almost a mile away. And being Maryland, he was charged with manslaughter. And back in 2011 an Ohio girl was killed from more than a mile away by a .22. It happens way more often than it should, and really makes me wonder when I see the rabble firing their Kalashnikov's into the air. Where does all than lead end up falling to the ground.
What it comes down to is that a little piece of lead will retain lethal energy over a very long distance. A 22 LR firing a common 40gn load has 110 pounds of muzzle energy. And based on the video still has more than half of it left at 440 yards. It's the velocity that gives it the punch, starting out at around 1100fps. And being so small in frontal area, the .22 retains it's velocity for a long distance.
We use a similar 40 grain bullet to hunt groundhogs. It's a copper jacketed ballistic tip that gets pushed to 4000fps and more than 1400 pounds of muzzle energy.
The old 5.56 that some may have lugged around at one time or another originally fired a 55 grain full jacketed 22 caliber bullet and had about 1200 pounds of muzzle energy.