When you have legs on a chair, table or any other project, you start out with a rectangular piece of wood. That is however not really attractive to look at. What you want to do is to curve the leg to make it look better. In this video he shows us how to curve a leg, mostly using a block plane. In my opinion this is a great skill for any woodworker to have. You tend to get a big difference in the look of the project without have to invest a really large amount of extra time or effort.