Watch the The Climb online guitar lesson by Freekbass from 50 Freekbass Licks You MUST Know
This style of thumping is where you thump the root note, and then pluck a fill to go along with the root. The progression goes from D to F to G to C. The same way an acoustic guitar player might hit their bottom string bass note, and then do something either with a chord or run with the other strings, you are doing the same. Root note thump, fill, root note thump, fill, etc.
I wanted to keep the fills both rhythmic and melodic to keep them interesting and not just filling up space. Also, I wanted to give each fill a little different feel and technique, so, using my drum analogy again, I wasn't hitting just the floor tom everytime.