An introduction to the mechanics of bitcoins and an overview of how transactions take place.
More free lessons at: http://www.khanacademy.org/video?v=Y-w7SnQWwVA
Video by Zulfikar Ramzan. Zulfikar Ramzan is a world-leading expert in computer security and cryptography and is currently the Chief Scientist at Sourcefire. He received his Ph.D. in computer science from MIT.