I wonder if he had to pull an extra permit!
That video appears to have been taken on a commercial high-fence farm. There is usually no permit or license required, but the hunter probably had to pay an extra fee for the second deer. These deer were does, so the fee would likely be only a few hundred dollars. Trophy bucks on such farms can run upward of $20,000, believe it or not. It is a high dollar business.
This was not a great shot. The second deer was accidentally hit by a bullet that was deflected as it passed through the first deer. Luckily, it was hit in a vital spot, so it didn't run off wounded.
As a passionate lifelong hunter, I don't consider taking game at a high-fence operation to be hunting, but it's legal, and if someone wants to buy a deer or other animal for meat or trophy, it's fine with me. In those situations, they are simply livestock.
It's really amusing to read the DUmmy reactions. I'm not sure even one has ever hunted. The ones trying to defend hunting, because they know that's where the votes are, don't know how. They cannot believe that a big-game animal isn't always killed instantaneously; they have no way to relate to the real world. No hunter allows game to suffer unnecessarily, and they did not in the video. In fact, both deer were apparently killed in their tracks. That doesn't mean they are instantly motionless. Sometimes they are, sometimes they are not. No hunter will shoot an animal a second time unless necessary, because high-velocity bullets cause wasted meat.