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A three-minute excerpt from Milton Friedman's Free to Choose in which he uses a pencil to show that no single person knows how to make it. He argues that the free market coordinates countless strangers peacefully.

A 1937 GM-produced film explaining how the automobile differential lets wheels turn at different speeds around a corner. It uses clear animations and cutaway demonstrations to build the idea from first principles.

A short video from the trafficwaves.org site showing how traffic jams and standing waves form, including the fight between cheaters and blockers at an exit-lane backup. It also touches on how individual driving behavior affects the flow.

A short clip from Carl Sagan's Cosmos in which he explains how Eratosthenes measured the circumference of the Earth using shadows in two Egyptian cities. It is a clear, visual account of an ancient scientific feat.

A short clip of Richard Feynman explaining how a train stays on its tracks, through the conical shape of wheels and how it handles curves without differentials.

A four-minute 2006 explainer on trusted computing, describing what it is and whether users should support it, with a skeptical DRM angle.

A one-minute clip about Paul Otlet, the Belgian bibliographer who in 1934 imagined users accessing a remote database through an electric telescope over a phone line. It presents his vision as a precursor of the web.

A short clip from the 1983 BBC series Fun to Imagine in which Richard Feynman explains how a train stays on the track. He covers the geometry of tapered wheels that steer the train back toward the center of the rails.