I thought of a solution, if you really want to prevent phpmotion from being used as porn you should set a price, a ridiculously high price for a license to use for a porn, like let say $50,000, no one would pay that much, but the important part is in the case someone uses phpmotion with out the license you have a basis to sue them from, for $50,000, which I doubt anyone would want to pay, they would probably switch scripts from the mere treat of a lawsuit, you could even settle for like $500 and their commitment to switch video scripts. Am not a lawyer so you should consult one first but it would seem to work. You would probably have to see if that would constitute discrimination against a type of business