The following list is a compilation of interesting videos related to mechanisms that I have found on YouTube over the years.   None of these materials have been created by me.  When possible I have named the author of the video in order to acknowledge his work.  Thanks to all the creators.

Law of the lever

Theory explaining how a lever works and the law of the lever.  They also present an interesting experiment in order to demostrate how a general lever works.

Authors: seta.ie

Simple Machines: The Pulley

Jared describes how different types of pulleys can make our work easier.

Authors: FunScienceSupport

How Pulleys Work

A example of a simple pulley system and how it works.  

It shows in a clear way how a simple block and tackle mechanism works.

Author: Charles Marzzacco

Pulleys and Gears - Part 1

Informal resource video for elementary science teachers based on the Ontario science curriculum unit about pulleys and gears - Grade 4

Author: SciEducation

Pulleys and Gears - Part 2

Informal resource video for elementary science teachers based on the Ontario science curriculum unit about pulleys and gears - Grade 4

Author: SciEducation