I guess it's just muting. I tend to rest the meat of my hand (the chunk between my pinky and my wrist) on the strings over the bridge saddles. Then I can thumb pluck and use my index, and middle finger to play the higher strings. With this, I dont have to move my right hand too much at all, and can reach every string on my Fbass 6'er (which has really wide spacing).
but yeah, in terms of the bass line, it's just thumb plucking with the strings partially muted. And it's accented with hammer ons and pull offs with my right hand.
Glad you liked it.
jake
www.jakewolfmusic.com