This is a clip from the movie “The Hudsucker Proxy” (1994). In the scene, the store owner have a hard time selling the Hula Hoop. He kept lower the price but still no one wants to buy the Hula Hoop even he end up giving them for free with any purchase. He then throw all them out of the store and one of them accidentally bump into a boy. The boy start playing with it and the other kids saw it. After that, they all run to the store for the Hula Hoop. As more and more kids tried to buy a Hula Hoop, the price goes up again and even higher than before.
This related to the idea of demand and supply. At first, the Hula Hoop was not popular for kids so there’s no one wants to buy it. However, after the kids saw the boy playing with it, their preference change. Preference can change the demand of a product. When the demand increase, the price of the product and the supply also increase.
Thanks for the clip and summary Yi Chun Liu.