It's quite a bit of animation there, but I think the basic look could be created by using the scribble effect. Check out these tutorials for more info on scribble.
Johnny Cuevas, Editor
"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.