RQ: Megacrush on Forgotten Worlds PS2

[Kollision]

I beat Forgetton Worlds twice on the Capcom Classics Collection (PS2) and I still don't know how to do the "megacrush", the attack that kills everything on-screen at the cost of a little chunk of health.

To have an idea how it works, check this video (in a few seconds the drones coming from behind will be toasted due to the megacrush):
http://www.youtube.com/watch?v=pRHegI2YqA0&t=3m50s
.
I have tried everything but I just feel stupid because I couldn't figure out how to do it....
I think I did it only once by accident on the first stage, but that was even before I cleared the game.

Help?

[saucykobold]

Double-tapping the fire button should do the trick.

[Kollision]

Thanks, saucy.

I knew I would feel stupid