How infectious is that virus? How good is free birth control? How much should you worry about supplements? Watch and learn! For those of you who want to read more, go here: http://theincidentaleconomist.com/wordpress/?p=58849 John Green -- Executive Producer Stan Muller -- Director, Producer Aaron Carroll -- Writer Mark Olsen -- Graphics http://www.twitter.com/aaronecarroll http://www.twitter.com/crashcoursestan http://www.twitter.com/realjohngreen http://www.twitter.com/olsenvideo