Wow! Careless movements around firearms produce unwanted results. I feel for the guy, at least he his hit a big mass muscle groups and not the front of the leg that he could do real damage.
Trigger finger discipline! Always,always, always!!!
Also, never try to do anything else with the hand holding a gun. Put the weapon down or use the other hand.
No wonder Isrealian carry is trained to not have a round chambered.
Glad it was just his leg. Ouch.