Imagine a scale of do-re-mi-fa-so-la-ti-do. Got it? Good. The chord rooted in the "do" is known as the "tonic" (roman numeral I), or the chord that sets the tone for the whole scale. That which is based on the "fa" is the "subdominant" (roman numeral IV), and the one based on the "so" is the "dominant" (roman numeral V). So on a natural C scale (A, B, C, D, E, F, G), the three primary major chords (I, IV, and V) would be C, F, and G. Oh, and roman numerals rendered in the lower case indicate the minor, not the major chord.
That's a rather crude explanation, but it's one that can be transposed to other scales, so it will serve us for now.
Our first two video clips deal with a curious phenomenon of the many pop songs in recent memory which consist of just four chords. They are: I, V, vi, IV. In the example provided by the Australian trio "Axis of Awesome" in the first clip, the chord progression appears to be E, B, C# minor, A. They demonstrate this phenomenon for the following:
You're beautiful by James Blunt,
Forever young by the Alphaville (covered by Youth Group),
I'm yours by Jason Mraz,
Amazing by Alex Lloyd,
Wherever you go by the Calling,
Can you feel the love tonight by Elton John,
She will be loved by Maroon 5,
Pictures of you by the Last Goodnight,
Cigarettes will kill you by Ben Lee,
With or without you by U2,
Fall at your feet by Crowded House,
Am I not pretty enough? by Kasey Chambers,
Let it be by The Beatles,
Under the bridge by RHCP,
Horses by Darryl Braithwaite,
Down under by Men at Work,
Old Australia's funniest Homevideos intro,
Taylor by Jack Johnson,
2 become 1 by the Spice Girls,
Take on me by A-ha,
When I come around by Green Day,
Save tonight by Eagle Eye Cherry,
Africa by Toto,
If I Were A Boy by Beyonce,
Self Esteem by the Offspring,
Apologize by One Republic,
U + Ur Hand by Pink,
Pokerface by Lady Gaga,
Barbie Girl by Aqua,
Kids by MGMT, and finally,
Scar by Missy Higgins.
Still with me? Excellent!
Someone else known only as "mathyou9" took this a little farther in our second clip, and found as many as 65 songs which use this same chord progression. Over and over and over, for nine minutes.
Around the world is an army of hungry recording industry lawyers, just licking their chops at the thought of taking on the sort of imitators we have described here. But they should know that what we show here is not without historical precedent. A variation on the aforementioned phenomenon is the EIGHT-chord progression, as found in "Pachelbel's Canon in D" according to comedian/musician Rob Paravonian, the subject of our third clip.
As a musician, I've always regretted never having developed the knack for songwriting. After seeing this, I can't imagine what stopped me all these years.
Obviously, Led Zeppelin was right all along.
[FOOTNOTE: In music, the frequency of the standard pitch A above middle C on a piano is usually defined as 440 Hz, that is, 440 cycles per second. This is known as concert pitch, to which an orchestra tunes.]