Allan Sloan a Senior Editor at fortune magazine explains how lenders were able to issue subprime mortgages to borrowers.

Richard explains file compression and his new "Middle Out" algorithm at Pied Piper's pitch at TechCrunch.

Sheldon, Howard, Raj and Leonard discuss time travel in the movie Back to the Future and the proper tenses verbs to describe their actions

John Green explains the beginning of the US government, Washington's Presidency, and the start of Political Parties.

This clip discusses the many impacts that space debris has caused on the planet Jupiter and how these collisions work.