We are covering radical forms of Islam in my World Religions class. Here is an excellent overview of Wahhabism, a radical form of Sunni Islam that started in Saudi Arabia.
The clip is less than three minutes and comes from the Discovery News Network. Alistair Crooke , in an article for the Huffington Post, argues that we cannot understand ISIS if we don't know the history of Wahabbism.
The article includes another short video clip about the connection between Saudi Arabia and the development of Wahabbism, which you can see below.In addition, PBS Frontline has excerpts from interviews with a number of people familiar with Wahabbism and The New Statesman has a great story about the connections between ISIS and Wahabbism called, "Wahhabism to ISIS: how Saudi Arabia exported the main source of global terrorism."