I understand your request but the video should be self explanatory, isn't it?
However I try to translate the introduction of the video from it's original language:
"The video tells the story of the Good that, once placed in a circle, comes back to who did it. As in the case of a young girl who wants to give to her grandfather the birthday cake but she has not enough money. It will be a boy to give her the money, asking her the promise that one day she will have the same attention to someone else in need. A promise that the boy made years before, and so he keeps closed the circle of Good"
As far as I have understood, the grandfather is the man who helped the boy years before.