Notice how in the example clip the guy misses almost all shots on me while I'm doing the ras strafe, compared to when I am on the ground strafing normally.

Recap:
(This is for right to left)
Forward pattern D + scroll down + scroll up + W + A + S
Backwards pattern D + scroll down + scroll up + S + A

Note: I have scroll down binded to jump and scroll up bounded to W