DAC and ADC explanation

https://www.youtube.com/watch?v=cIQ9IXSUzuM

This is a good video that explains how audio signals are sampled and represented digitally, and what effect that has on the final analog output.

Armoured Octopus

Buster Keaton

http://imgur.com/gallery/Bcg77

PBS Frontline: The Warning

http://video.pbs.org/video/1302794657/

PBS Frontline about the 2008 market crash.