I know they palm mute A lot, but is there any other techniques they use to get that "reggae" sound.
specifically in this song. i want to play it so bad
ESP LTD EC-1000 vintage black
sunburst fender MIM tele
Epiphone LP standard ebony
Mesa/boogie dual rectifier
Mesa/Boogie .50 caliber plus head
Marshall JCM900 Hi-gain MII 2500
Fender Hot rod Deluxe
No palm muting in this song....it's all about deadening the strings by muting them right after the chord is struck with your fretting hand on the upstroke.

In the video it looks like hes playing the chord on the downstroke, and then quickly muting the strings on the upstroke.

Hope that helps.
This is pretty simple. ALl you have to do to get that sound is relax your left hand to mute the strings.

Hit the strings - relax the left hand. Tighten it up, hit the strings, relax the left hand. Very easy technique.