hey Anakin,
I listened to the song and am pretty sure they are playing in A major, the intro starts off in E major and slides to D major. By the way Im just a beginner at playing the guitar.... a friend of mine who is pretty good at playing the guitar said that, if I wanted to learn to play a song that i like, i should listen to the bass line of the song and try to match it by following with your low E string on your guitar. Does that make sense? When you figure out all the bass notes to the song you then convert the bass notes to barre or open chords on your guitar. And when you get all the basic chords, you can start to add the intricate parts of the lead guitar..... i hope this info will help out and get you on your way to play this awesome song....good luck