Case of the Four Chords

It's strange how memory works, I don't know how I can still remember all the music theory I learned like 4 years ago but not be able to recall a single thing about cultural materialism (anthropological theory).

ANYWAY memory problems aside, I am sure many of you have heard about this awesome song called "4 Chords" by the rockin' Australian band Axis of Awesome. If not, here it is:

The most common question on all of the comments are WHAT ARE THE FOUR CHORDS? The actually give you the answer at the beginning of the video, but I will explain it anyway:
In any key there are 7 notes. This progression contains  the chords of  I,V,vi,IV. The song is in the key of E major, so we have the notes: E, F#,G#,A,B,C# and D#. SO, the magical chords are E,B,C# minor and A. :)