No, but a possession of any kind of media should not be a crime by itself. Nobody is harmed by a video/picture sitting on your hard drive. If you say that it might encourage anyone to do anything - then why is it perfectly legal to have videos of murders and gore?
Right, you may not even know that you have such media sitting in your browser's cache. All it takes is clicking on some link in a spam message, for example. Even if you immediately close it, the damage is done and you don't even know it.
