Weird Drawings Appear in A Child's Book

This video showcases a magic trick that has been around for a good 20 years, probably longer. Although it has been performed extensively by professional magicians, it has also been made available in a smaller version for children to handle.
A colouring book is shown to have all blank pages.
Suddenly, there is a black and white drawing on each page.
The magician then proceeds to bring colour to the drawings, decorating them in a bright array of many shades.