Troubles I got with it, my movieclip, which was drawn from, was centered – so all content from the left side of the pivot point wasn rendered.
Just replace the first 2 lines of the constructor with this to remove this effect:

bmd = new BitmapData(srcDispObj.width, srcDispObj.height);
var m:Matrix = new Matrix();
m.translate(-srcDispObj.getRect(srcDispObj).x, -srcDispObj.getRect(srcDispObj).y);
bmd.draw(srcDispObj, m);

I did ran into a problem. The Mosaic filter works fine when running locally, but as soon as I place the swf on a webserver, the Flash movie halts at the moment of creating the class instance. Any clue what goes wrong here?

Great class, very nice work – short, sweet and effective!

One question, though – the pixelation happens from top-left (0,0). Any chance of pointers to get it working from another position, say perhaps the centre (but ideally any co-ordinate)?

thanks