Is the warp speed lifting accompanied by atrocious form? Like the bicep curl lady - is she getting her legs and back into it and really swinging those DBs up and down? I'm no expert, but when I see that superfast lifting, it's usually too much weight done with terrible form. I think the speed gives you momentum to haul up too much weight - often you see people like that flinging their bodies around and getting all sorts of help from body parts they're not working. It's a wonder they don't hurt themselves or others, but I guess they're impressing themselves with how much weight they think they're lifting.
Or else she could be lifting that fast because the weight is so light that she's not at all challenged by it.
I try for *very* controlled lifting, not fast or slow, resisting the negative, with no swinging or momentum. I may not lift as much weight as the speed demons but I think I get a lot more out of it.
But I'm no expert and maybe there are legit reasons to lift that way.