The comments from the YouTube video page:

We had been on the ground tracking with the bushman, lost tracks and were leaving the area. This lioness was not the target, but as you can see it was necessary to shoot.

We were alerted by the growl as we slowly drove through long grass. As my long time PH friend, Gene Small, later said "When a lion's tail moves that way, it's coming no matter what."

I was using a very unique, one of a kind rifle made by Nowatny. See Double Gun Journal Autumn 2007 article by Sherman Bell (Not English make). It is an ejector drilling designed especially for dangerous game hunting. The top barrels are 2 ž inch Super Magnum Explora for a Paradox style bullet and the bottom barrel is a 400-360 Westley Richards Nitro. My Super Magnum Explora regulated with 860 grain bullets at about 950 FPS. The 400-360 Westley fired a 310 Woodleigh bullet at 2125 FPS. The drilling has an original claw mount system and a modern Zeiss scope. Its weight is 10 pounds with scope. The rifle was purchased off of http://www.gunsinternational.com

I only loaded the two top barrels (mistake). I shot the lioness in the chest, took the heart and the 860 grain bullet stopped under the hide in the other end. She came at us quite furiously and instantly. I fired again only hitting her through the skin on the back having no effect on the charge. Another P.H. fired and hit the side rail of the truck (hear the metallic ping on the video) at the last moment. She then jumped on the truck with us and I held her off with my empty gun barrel for one to two seconds until she fell off and expired from the heart shot. Her paws and mouth were only a couple feet from our faces and the truck and were covered in blood.

As a comment, the three trackers were nowhere to be found. But most importantly, PH Eugene Small (ES Safaris) never stopped filming even when this deadly threat was less than two feet away. That was a close one, we're not professional camera folks, this is just what happened.