The bass player is Nathan Navarro, and he is a real innovator. We interviewed him shortly after this video. This is from our blog on Nathan:
The first video has Nathan getting his dubstep wobble on an all-bass original tune. Describing his pedal board set up for the video, he says, “I ran my bass into a Boss SYB-5 and used the Hot Hand Midi-EXP for the expression input. I don't think the SYB-5 is intended for LFO stuff but it worked alright as a mid-rangy wobble. I'm still working on getting the lower frequency wobbles... BEF for the win. After the synth pedal I also added some distortion with an Ibanez Phat Hed overdrive (not the best distortion pedal in the world but it worked okay). Also, I made sure to keep some of the original clean output going through the mix.”
So, he uses the Hot Hard MIDI-exp in this video but in more recent videos it has been the Hot Hand plus BEF.