Every autumn people tour Maine just to see the leaves changing color. Seeing the leaves change is one of my favorite things about the fall too. Here are three good videos that explain why leaves change color in the fall.
Untamed Science offers a good, partially animated, explanation of why leaves change colors, what produces the colors, and why bright and sunny days are best for viewing red leaves. The video is embedded below.
Reactions, a great YouTube channel from the American Chemical Society, offers a nice video about the chemistry involved in the process of leaves changing color. The videos explains how chlorophyll and the glucose stored inside trees help reveal the reds, yellows and, browns of fall foliage.
SciShow Kids offers the following video about the science of changing leaves.