"No" means "no," and "go away" means "go away."
There's a point at which young love tips over from being adorable to being annoying. It's an extremely distinct point that shouldn't be at all difficult to find: it's the point right after you've been rejected, which is fine, and right before you keep going, which is not.
The very idea that you can win somebody's affection at all is a kind of dangerous myth. Okay, maybe you can win somebody's company by beating them down with romantic overtures until they agree to spend time with you, but you can't force them to enjoy it. The more likely scenario, though, is that they'll start actively avoiding you, and you'll end up losing not just their friendship but your own self-respect.
Here's the reality: somebody who genuinely likes you in that special way doesn't need to be convinced to reciprocate your affection, and if they don't like you in that special way, then that's that. Maybe one day, something will click in their head and they'll suddenly discover an untapped well of affection for you, but I promise you that it will have nothing to do with you embarking upon an ongoing campaign for their love. In fact, such behavior would almost certainly prevent them from changing their mind.
So, whether you're the boy the woman in this video is talking to, or some other person being similarly annoying to someone who is not this woman's daughter, you have to digest this advice: let it go.
And you know what? When somebody does come along who feels for you the way you feel for them, you'll be amazed at how easy a relationship can be. No begging, no stalking, no crying. Just pleasantness.
Guy who learned this lesson the hard way