This is rather stupid, considering the director of Downfall watches them and likes them. In fact, in his own words "I think I've seen about 145 of them! Of course, I have to put the sound down when I watch. Many times the lines are so funny, I laugh out loud, and I'm laughing about the scene that I staged myself! You couldn't get a better compliment as a director." http://nymag.com/daily/entertainment/2010/01/the_director_of_downfall_on_al.html
Well... The article also ends with the director saying "If only I got royalties for it, then I'd be even happier." But removing the videos from youtube wouldn't help him with getting royalties, so yeah. It is rather stupid. He'll probably get less money now since the videos were essentially free advertising for the movie.
"Don't worry about people stealing your ideas. If your ideas are any good, you'll have to ram them down people's throats." -- Howard Aiken