Fernando "Terere" has been known as a great "sweeper" in BJJ. In this video clip he shows a lot of his adjustments and details of what make his "butterfly" sweep work.
https://www.youtube.com/watch?v=gt0fQlfdyI4#t=142
Kid Peligro Iphone App Secrets of the Closed Guard
https://www.youtube.com/watch?v=gt0fQlfdyI4#t=142
