I had a short piece of copyright video removed from YouTube because it was owned by some major motion picture company. It was less than 15 seconds long. My understanding of copyright law is that copyright material can sometimes be considered to be "Fair Use" (whatever that means) and allowed to be used by someone other than the copyright owner. Is this true? Is there some appeal? What are the rules here? If the movie clip was only 3 seconds long, would it still be prohibited?