To say that Glocks are less reliable than the others, based on those videos, is stretching it. I have never personally seen anyone grip a pistol like that, I don't know anyone who would, and it doesn't fit the typical definition of limp-wristing. It's a stunt, basically.
Also, in my opinion, it's poor firearms safety and irresponsible of someone to make such a video and put it on the web because some fool is gonna try it and put a hole in somebody! Those videos do nothing to promote a positive image of the gun-owning population. Of course You Tube is full of that junk.