Sir Paul Nurse - Great Ideas of Biology
This is an hour long talk by Nobel prize winner Sir Paul Nurse, who has a rather Monty Pythonesque delivery style of explaining concepts to the lay person. He explains great moments in biology - the cell, evolution, the gene and biological complexity in terms anyone can understand. After watching this you'll have a much greater understanding of how and why things work the way they do. On a personal note this is one of the best talks I've seen in a very long time. Highly recommended.