To be honest I've never heard of Nico Nico Douga, but thanks for telling me about it. Gotta make an account anyway ^^
A few years ago German anime adaptations were pretty well done. Especially the Digimon series ( btw, I only really like Tamers, was never a big fan of digimon yet I saw all episodes of all series for some reason ^^).
For many reasons the dubbing quality started sinking in the last few years and the German naruto dub shows this pretty well ( it felt VERY 4KIDS-ish). The only good dub right now is probably One Piece which is almost cut-free nowadays and YuGiOH 5Ds which finally uses the japanese version as source material ( I don't like 5Ds, so this isn't anything to write about honestly).
It is cool to hear that German version of various anime openings in themes are so well accepted around the world. When I first listened to the US version of the very first Digimon opening I think something died inside of me -.-