How does he do it? I've tried every possible combination of inputs, but I can't find a way to do that attack, which makes the fight significantly faster.

No dash, neutral □x2 or neutral □x2→A little dash→neutral □x2. Depending on the controller, it may be difficult to launch such a neutral □ attack.

At this point of the normal WR video, the attack is stopped in the middle and OTK is done.