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David Spiegelhalter, Professor of the Public Understanding of Risk, uses statistics to weigh everyday risks such as bacon sandwiches and cycling. The six-minute piece introduces micromorts as a way to compare the risk of dying.

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.

Michael Wesch's five-minute video about Web 2.0, showing how the read/write web, XML and user-generated content change how people create and share information.

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 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 video built around an animation of the roughly 10,000 galaxies in the Hubble Ultra Deep Field, placed at their measured redshift distances. It gives a brief history of deep field images and ends with a 3D fly-through.

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