Interesting video. Educational, and almost disastrous. Interesting the buff that is down let the other one work him over without reacting much........ then a sudden resurrection when shot again.
Like has been said, "it's the dead ones that kill you."
American bison bulls will also work over an animal that is down. It's a behavior that's pretty strange to me.
There's potentially lots to critique, but possibly the PH should have been ready to shoot and shooting as he got up. With cover so close, it's an either-or situation though.