Billiard Balls

Hume uses the example of the billiard ball to explain the process of cause and effect. He says if one sees one billiard ball rolling toward a second billiard ball, can it be predicted that the second billiard ball will move when hit? He says no since it has no indication that it should behave a certain way based on observation alone. Also, just because in the past you have seen the billiard balls bounce a certain way, it doesn't mean that you can infer that they will do the same action this time...