Click the green flag and the speedpaint will play. To replay, press the green flag again. :D
Tbh, this took me less than an hour. I decided to create my very first speedpaint, and it turned out to be quite easy. And you can see inside my project and refer to it if you are interested in making your own speedpaint :) I sped up the speedpaint because I thought it would look more natural but comment if it feels too fast!