Youtube Content Removal
This article explains why the famed Hitler parodies were removed from youtube. Basically what Youtube has come to say is that they use an automated content filter in order to track and detect copyrighted material and remove it from their site. They still have the video and can quite readily re-enable it, but you must file an appeal to prove that the material you have posted is allowed to be posted online via fair use regulations.
Youtube would rather wrongly pull something that is allowed to be posted than allow everything to be posted and be sued by the content owner for copyright infringement.
