I wish I could shoot like Mr. Kelley, but if you watch enough of his video's, the thing that cracks me up is he keeps dropping the mag out of all kinds of pistols in the middle of a string of shots.
He explains the problem he has early in that PX4 .45 video (he reversed the mag catch on the .45 PX4 to keep it from happening), a lefty with large hands that can reach around to the mag release, but in the video on the 9mm version of the PX4, he drops the mag while shooting two or three times.
As a righty with small hands, the idea of this happening is so foreign to me, it's something that really sticks out when it happens to him.