Ouch. He's better than the stay-at-home boys who play video games....I'm thinking.....
Anyway, I think those retention holsters where you have to press the little dealie (OK, latch, whatever) to release are an accident waiting to happen. I have a couple and when I started to use them I immediately saw the potential for an early bang. So...I draw more slowly when I use them and am very deliberate about it....on the defense drills like that guy was running when he shot himself I go really slow. I've changed out one of them and will soon change out the final two when I get a few $$$$$'s.
The one exception may be on the FN Five Seven since it's safety is on the frame forward of the trigger where the finger should be resting when not actually on the trigger to fire. It's a really quick safety too since the booger picker is resting on it whether on high or low ready and it swings down on the way to the bang switch.