I guess the problem here is the position x and y of your effect..
Seems like they are based on screen(window)-coordinates, rather than project coordinates..
So to scale the effect you should move those coordinates..
Not sure what you want though..
If it's the middle of the screent, it would be simply windowwidth/2, windowheight/2
If you look at the preview of the effect provided in the thread and scale the window (browser) manually, youll see the same issue..