I am deeply sorry for this song I have not yet found a video on either YouTube, Google videos, Veoh, Dailymotion, ClipVN, or any other video browsers. It seems that no one had posted the video for this anime song opening, but you could search for it if you like, I hope you find it~
Although no one can teach you on video, I know the song by heart by now. I can tell you that you could figure out how to play it by ear, and test out the notes. You could try sythesia videos which teach you the notes by a piano with indicators for keys to play, which you could make your own piano music sheet or you can have a laptop and play with looking at it. This would help. This song is very strong, so you should try to accent it at most times and make the feel. Listening to the song with a singer would help to know the accents. Be skilled, this song isn't easy!!