Roberto Perez Rivero gave an excellent presentation at the Tenth International Permaculture Conference (IPC10). Watch it below. As the projector wasn't the best, you may also want to make use of the links below to download the slideshow from this talk so you can click through those in a different window as Roberto speaks:

P.S. The video starts in mediocre quality, but after a few minutes jumps into higher resolution.

Presentation Files:

• Slideshow (115mb)
• PDF (29mb)