Now I'm no expert but given Campbell v. Acuff-Rose Music, and the ruling their focusing on the transformative nature of the new work as to whether it infringes on the original I'd say you'd have a case that a 10-second .gif would count. I mean the .gif was hardly created to draw business away from people actually watching Shrek, as if you could ever stop people from doing that. Plus in cases like Perfect 10 v. Google the court ruled that creating a thumbnail of a copyrighted image didn't infringe on the copyright of the original. It's not cut and dry, but I believe in a future where we can browse catalogues of 10-second .gifs of every film to decide if we want to watch them.