I have shot a lot of steel targets over the years, but never rigidely affixed ones. I hav never seen anything like this personally. The targets I have shot at have always been low mass and mounted to absorb the energy of the impact by swinging or falling over when struck. It is like the difference between throwing a tennis ball at a brick wall, and throwing it at a blanket hanging from a cloths line.
I have shot at several ranges with rigidely affixed bullet trap plates which are designed to bounce the projectiles, but in a controlled fashion into a common catch area and not back at the shooter, or anywhere else.
There are a lot of things not shown in this video, like the exact nature of the target and impact area/backstop. I don't think a single bounce 180 degree ricochet is really possible IE: bringing the projectile mass to a complete stop then directly reversinging, and accelerating it back along it's original path. You heard him hit the metal target. It would be my guess that the projectile deflected off at some angle and struck something else in the target area for a second bounce that sent the now very distorted projectile(you can hear the warbling sound of it flying thru the air in the video) back at the shooter. Suffice it to say that they were not using a safe target and backstop(exposed rock probably produce this result), and were just plain lucky... Cool video though.