Superb work!
Just felt like throwing my opinion along with the batch. The aspect about this that I enjoy the most is the sheer clarity of the animation. The smooth nature of the animation itself, the direction of the video, how well syncronized the video was with the music selection, and so forth.
The one quality about this that I enjoy the most is how it doesn't look or feel like a flash animation. This is crutial as to why it is so well recieved, in my honest opinion. Instead of feeling like a well animated work comprised of a lot of digital cels integrating within eachother, and unfortunately giving away the nature of a 'typical flash animation.' This is very evident especially if a flash animation is put onto television. This work focuses so much on the sheer mechanics of the animation to drive it forward, giving the feel of something more than the standard approach to Flash. It's beyond that.
It is for this reason why I enjoy this work moreso than the Rise of the MK series. Sprite animations, while awesome to watch, all /feel/ like flash animations. This doesn't have that quality, and deserves the rank it currently has.
Top notch work, enough of my rant, and for some of those who don't seem to get it, there /is/ a difference between Korean and Japanese.