@GunskiMod Go into a map with low gravity. Stand in one place. Jump, use A and D and right and left mouse movements just like you're bunny hopping. You'll see that every iteration of the bunny hop while you're in the air speeds you up more. This is air strafing.
@nexus1g I know how to bhop/strafe. I'm talking about when he's in the air, he shakes his mouse. All you need to do is move your mouse in one direction.