I wonder why no one did this before? The NicoNicoDouga Ryuuseigun is the most famous mega medley on NicoNicoDouga. This version features Miku, Kaito, Meiko and the Kagamine twins performing it from start to finish. Enjoy![youtube:http://www.youtube.com/watch?v=Ssxz2FQhs7M 463 392]
Note: Due to the 15 minute runtime this video had to be split to two parts. Linked above is part one.