I'm new to music theory, so this is confusing.
In the key of Eb, the I-IV-V major progression is Eb, Ab, Bb.
What I don't get is how this song uses the major I-IV-V pattern,
yet minor chords are being played. So instead of Eb, Ab, Bb it's
Ebm, Abm, Bbm?!

Look at it as i-iv-v
or
i-iv-V(raised 7th to resolve back to i)

You have to understand your scales and how chords are built.
Quote by blakeg14
I'm new to music theory, so this is confusing.
In the key of Eb, the I-IV-V major progression is Eb, Ab, Bb.
What I don't get is how this song uses the major I-IV-V pattern,
yet minor chords are being played. So instead of Eb, Ab, Bb it's
Ebm, Abm, Bbm?!

it's in the key of Eb MINOR. Minor keys and major keys both have very workable I-IV-V progressions, (i-iv-v or i-iv-V in minor).
Bear in mind that I-II-IV-V are the notes that will be the same regardless of whether the scale is major or minor. (Yeah, yeah, minor second, I know, nobody uses it outside of metal.) Plus, lots of people use major chords when playing in a minor key for a different texture, so why not do the opposite?
EDIT: ninja'd by a duck. A ninja duck. What?
the I - IV - V pattern is common in both Major and Minor keys
but this song is in Eb minor like stated above

Quote by Gunpowder
Thrashturbating? Most metal of all ways to pleasure oneself.
It's just using the primary triads of the natural minor scale.

The harmonized major scale is I ii iii IV V vi viidim
The harmonized natural minor scale is i iidim bIII iv v bVI bVII

As you can see, the 1 4 and 5 chords of the major scale are all major and the 1 4 and 5 chords of the natural minor scale are all minor. So what this means is if you play in a minor key (without accidentals), your primary triads have to be minor.
Only play what you hear. If you don’t hear anything, don’t play anything.
-Chick Corea
Quote by duck1992
it's in the key of Eb MINOR. Minor keys and major keys both have very workable I-IV-V progressions, (i-iv-v or i-iv-V in minor).

Ohh ok, I see now. Thanks!