at 4:10 you clearly see his mechanics. There are a second peg for each one of them, that can detune of one tone, and I think you can see he can in addition pull on the pegs that have a special mechanism that brings it to its original place when released. It's like having a vibrato for every string.
Also, I think he has those "detuners" on the bridge too.
It reminds me of the "D-tuner", a system for floyd rose that allow you to detune your low string a tone lower so that you pass in dropped D at any moment without having string/floyd balance issue.