The fair use which in literal sense means to get something or other thing copyrighted and then exploits it, and secondly under the first amendment, it is considered to be a protected free speech.
Now what does fair use has to do with this?? Well the philosophy if fair use applies to the work of parody. The humorous imitation includes all the stuff you like by just getting it copyrighted as earlier said by the first amendment, it is a protected speech then let the people do not agree to it. Apparently, Hitler doesn't seem to follow this doctrine.
The producer of the movie "Downfall", Constantin Film Company which called forth the numerous of "Hitler finds out…" parodies in video mode had recently asked the You Tube to remove all the parody videos related to it. As Bruno Ganz's Hitler used a fumigating monologue in a German-language movie by the comic imitations which later made him realize that he was to lose the World War II.
The change in the subtitles appeared as if the Hitler was spouting every mere thing from the Amy Bishop's case to the video game errs. This led to a lot of complaints from various groups and also the Jewish advocates.