"A simple act of caring creates an endless ripple" comment

The video was really good. I think that the message of this video is that you have to help the people without hoping for something back.
The video starts with a mother that asks her daughter to go and find something special for her grandfather. She wanted to buy him a cake but the mother hasn't enough money so she didn't buy it. But then, a man who saw all decides to buy the cake and gave it to the girl. The mother asks him if he could give her his phone number because she wanted to pay him as soon as they got the money. But the man starts to tell her and the little girl his story: his story was the same thing as the girl's.
It follows that the man who bought the cake for him was the girl's grandfather, and when the girl arrives with her grandfather and shows him the piece of paper, he read the same message he wrote:
"A simple act of caring creates an endless ripple"
It means that in this life you receive what you give.