Without knowing anymore details, it is possible that this lion was a cull lion and instead of the authorities destroying it, they may have issued a permit to a local outfitter (I am speculating, mind you).
With medium or heavy rifles at this range, did they miss? or did the round scream right thru the animal. Wounded, enraged, looking for payback, a peripheral hit, just isn't going to do it.
Personally, I don't have any interest in hunting lions or aiding those who want to hunt them, but I will not condem someone based on a few minutes of tape or without further information than has been presented.
But, that is just me.
Note: after watching it again and again, How many people here, could make a shot on a moving lion basically screaming down your throat at 30 mph.
A friend did point out to me that most places in Africa that allow hunting require a 375 H&H as a minimum for dangerous game and that your guide has the last word on your shot and generally, you have a guide and they usually have a back up that works for them (tracker or for something like this) hunting lions is not for the faint at heart.