Damn, I had the "a" then changed it cause it looked wrong ' The video is a decent introduction. however, if you'd like to learn how to actually use them, a great resource is this free book: http://www.wardleymaps.com/uploads/9/5/9/6/9596026/future-is-predictable-v14.pdf, which was compiled from Simon Wardley's blog, takes you step by step through understanding the process, creating them, and using them to create a coherent business strategy.

If you have time for it, his entire blog is worth a look: http://blog.gardeviance.org/