I got scared at the end of the roll when his legs didn't appear to come to rest. He looked dead. Then I realized his leg was just too fat to come to rest against his other leg.
The ground is actually flat, what you're seeing is the curvature of spacetime via general relativity.
Also, rolling down a hill is a lot of fun and I think everyone should do it occasionally. I only wish I could generate my own incline in the tensor fields of the universe too.