I am hugely amazed at the speculation here on both sides. What I really found funny was the speculation that the lion was some sort of pest animal that had been causing problems and therefore needed to be dispatched. That may or may not be the case and the footage would give no indication either way. However, the fact that the primary shooter was being given instruction on specifically what to do and not to do gives me the impression that this was a guided hunt, a safari sport hunt.
If these folks were out to dispatch a troublesome animal for the benefit of the local community, I would be inclined to believe they all would have attempted to dispatch the animal as quickly as possible. While they might have let one person take the first shot, once the animal got up, the other people in the group would have shot the animal right then. They didn't. This was apparently some sort of safari and the only reason why anyone else in the party was going to shoot was when the animal posed a threat to the hunters themselves...and then you can see just how effective their fire was once they realized they were in danger.
As LAK noted, it would not be unexpected for even skilled hunters to miss a charging animal. Why? Simple. Most skilled hunters do not attempt to shoot animals moving at high speeds or have to deal with the sense of danger coming from the fact that the speeding lion is charging the the hunters. I know it is called "hunting," but as with the first shot taken, that sort of hunting is nothing but animal sniping. As with sniping, most snipers prefer to shoot at stationary or slow moving targets when at all possible.
What surprised me about the footage is that while there were several people with rifles in the hunting party and several folks opened up when the animal charged, nobody seemed to have anything faster than a bolt action gun to shoot. Given the number of hunters with guns, there were not very many shots fired as the lion charged. At least one guy can be seen trying to work the action on his gun, apparently after having fired(?), as the lion passes through the group and downs the one hunter.