Official comment
He's incorrect in that video; there is no "pressure sensitivity," the top is either "touched" or "not touched."
He has the brake setting set such that when he's pressed the top of the jog (same as pressing the play/pause button), the player doesn't stop immediately, but rather has a vinyl brake due to the brake timing.
The reason it STOPS the second time he demonstrates it is not because he's pressed harder, but because his hand rotated the jog ever so slightly, which is the same as if you were to scratch; the movement effectively counters any braking and thus sounds like a hard stop.
You can adjust the braking in the deck preferences within rekordbox.