Internal motivation > external motivation. Raise your kid in such a way that he'll want to get good grades, not for a reward from you, or because he's afraid of being punished if he doesn't, but because it satisfies him to achieve good grades and use his potential. A kid should feel happy and satisfied when achieving good grades, not relieved for not being punished. Likewise, when a kid gets bad grades, he should feel dissapointed for not having done the best he can (presuming he didn't), not afraid because his dad will punish him.

Asian kids watching this are probably like: "Man they got it easy!"

Internal motivation is most ideal but how they go about developing it is entirely dependent on themselves. I think the best way to control them is either by punishing them or by making them fear the circumstances without education ... 

Failure's take so many things for granted (shelter, food, sanitation, free educations, etc) don't realize that their ticking time bombs that can't diffuse themselves fast enough when they ought to be treasuring whatever chances they have ... 

That's the thing, the best way to control them doesn't matter, because the best way to go about it *isn't* to control them. 

In quite a few cases I would say it is ... 

Sometimes parent's do need to teach their kids self control ...

Yeah, teaching your kids self control isn't the same as controlling their reactions using fear. I mean, self control isn't being controlled by your parents. That would be... well, not the opposite, but it certainly wouldn't be self control. Emphasis on self.

It teaches them to be not lazy at least ...  

So there's a postive to be had in the end when they get good working habits plus they can choose to not heed their parents possible dark foreshadowing if they want ...

Warning your kids about the possible effects of bad grades is very different from cutting their hair (or worse, hitting them) to punish them.

As long as it's not physical abuse I don't mind however way a parent would handle bad grades ...

Sometimes you need to make your children more humble by crushing their ego ...

So mental abuse is completely fine? Taking away all their selfworth and self esteem is ok? Judging by that video, it seems like this isn't the kids first time in this situation, and their grades evidently didn't improve, so obviously whatever he is doing, it's not working aka it's stupid.