Computations involved in mining Bitcoin are astronomical. Professor Phil Moriarty explains how estimating the energy useage is a Fermi problem.
The paper Phil refers to: http://bit.ly/C_BTC-Energy
Onion Routing (Tor): https://youtu.be/QRYzre4bf7I
Bitcoin Mining in 4 minutes: https://youtu.be/wTC31ZI6QM4
This video was filmed and edited by Sean Riley.
Computer Science at the University of Nottingham: https://bit.ly/nottscomputer
Computerphile is a sister project to Brady Haran's Numberphile. More at http://www.bradyharan.com