The Jab

[SugarBoxing]

@Scrap

Fast hands thingy is a result of sinchronised feet / hip and hand movements, I cannot really explain short way, but I got it comparing Pacquiao vs Provodnikov.
Provodnikov is often not engaging feet / hips into his flurries, and as a result they are somewhat slow sloppy almos pure arm punching, while pacman (and young Tyson)
has very good feet/hip and hands coordination. This video you posted - I personally do not think it can really help (the method)