this will get you started, or may all you want:
function pixellateF(mc:MovieClip,pixelSize:int=2):Bitmap{
var bmpd:BitmapData = new BitmapData(mc.width,mc.height,true,0xffffff);
bmpd.draw(mc);
for(var xvar:int=1;xvar<=mc.width;xvar+=pixelSize){
for(var yvar:int=1;yvar<mc.height;yvar+=pixelSize){
var col:uint = bmpd.getPixel32(xvar,yvar);
for(var xx:int=xvar;xx<xvar+pixelSize;xx++){
for(var yy:int=yvar;yy<yvar+pixelSize;yy++){
bmpd.setPixel32(xx,yy,col);
}
}
}
}
return new Bitmap(bmpd);
}