Unfortunately I think this is false. Contemporary scholarship of the last few decades has questioned the assumptions and factual basis of the economic interpretation of the crusades to which Bob is alluding here (e.g. landless younger sons of the nobility went on adventure to win an inheritance). If anything, as I understand it, the current consensus of historians holds that the typical crusader would have thought himself as on a kind of pilgrimage. See the works of Jonathan Riley-Smith, for instance. On the other hand, Bob specifically mentions the motivations of rulers leading the crusades. I think it's fair to say their motivations were mixed, with a St. Bernard or a Louis IX having one kind of reason and a Frederick II having another.