The second video in the Physics Patchalong series takes you through creating and using constraints with physics bodies to add structure. Follow along as Rob Ramirez goes through the creation of a fully functional physics simulation.
Part 1: http://youtu.be/HSJpWD2Zx5w
Part 3: http://youtu.be/bArs9nnvGCw
Get more information on Jitter Physics: http://cycling74.com/physics/