I know people who were able to dunk in high school as teenagers and were very explosive. Than they started weight lifing regime, lifted hard for a decade (solid weights on compund movements), still can't really dunk no more, while they should be even more explosive.

Thing is, pylometrics is still nr. 1 for most explosivnes and also olimpic lifting, but not classis weight lifting, strength is not power.

+EDIT: This guy on the video does far more than just DL to achive what he does, he is also very competent at calisthenics, he does one leg hill jums and other extremely difficult exercises ... Claiming this is a product of solely DL is misinforming.