I don't know if more explaination is really necessary. (There's something to be said for short-and-sweet, especially in a FAQ.)

Besides, I think "If you want to make anime music videos you should pay for your source footage" is pretty self-explanatory. Anyone who doesn't understand why they should pay for their source footage will require more than a FAQ answer before the "get it".
Actually the first sentance could probably be dropped altogether. But maybe you could add another sentance about the video quality. So that may look something like:
"If you want to make anime music videos you should pay for your source footage. In addition, using downloaded footage often degrades the visual quality of your video, and therefore is unwelcome from an artistic point of view. Do not ask this question on the forums, as your account may be suspended or banned."
Anyhow, just throwing out another idea. There it is.
