This is a very interesting and beautiful musical compilation but the scholarship behind it is questionable. The Cathars were not a fairy people. They were dualists who believed in the simultaneous existence of good and evil, which has major repurcussions in any philosophical system. They were not early protestants, nor were they Occitanian nationalists. For more information I recommend the easily available "The Medieval Manichee," by Steven Runciman, and the much harder to find "The Bogomils" by Dmitri Obolensky. The Crusade against them was militarily speaking, a failure. See the recent "God's War: A New History of the Crusades" by Christopher Tyerman. I'm sorry I can't give books in French, but I'm sure you will find them. Au revoir.