What do you mean intent can't be measured? Of course intent can be measured, if one cares to do so. It's called asking a question / taking a deposition. If a person says "I was making an art project" and they monetize it, then the flight itself isn't actually the product. If the flight was for enjoyment and the video was a byproduct then how, logically, can one be prevented from monetizing it? I know this is really a fine line but art and commerce are often at odds in such respects.