Regarding those videos, could you explain exactly how are you grabbing the shirt and controlling it? I used to lift my shirt pretty high and basically race it back down to the mag, which is a lot of wasted motion while not having positive control over the shirt either. Your motion is so much more efficient but even slowing down the slo-mo version, there's too much motion blur for me to make out exactly what's going on...you're just too damn fast.
Specifically, what part of your hand lifts the shirt, and how do you ensure you get a clean grab on the mag, as opposed to getting the mag plus a handful of shirt?