The public service announcement is emotionally manipulative and strategically pulls at the most basic things everyone likes (cute kids! young love!) and might even be scripted and is definitely edited nicely but still, the message is something that even children know to be true: Domestic violence is not OK.
The video starts off as an interview for boys in Italy. The basic questions: how old they are, what they want to be when they grow up (a pizza maker! a baker!) and why (because he likes pizza! because he likes to make a mess!) and then a pretty girl enters the equation.
They're asked what they think about her, why they like her, to caress her (which actually raises a whole 'nother issue of the video showing that boys are OK-ish with harassment?) and finally to slap her. After a pause where you can see the internal logic and reason gears churning, they all say no to warm our heart.
Boys won't hit girls so why do some men think it's OK? Because, like the last boy implies in his answer to the question "Why didn't you do it?" they are not really men. They are cowards, subhumans. He didn't slap her because he is a man -- and that's how real all men should act.