the four pix...well...it had me confused as well until i remembered that for this anim I was playing around with having multiple styles of movement for different parts if the object. If you look closely, you will see that the very bottom piece is spinning opposite to the rest...
Guess I should fix that, eh?!?
What i have started to do for removing these pixels, is open the animation in ADOBE IMAGEREADY and frame-by-frame erase these pix. Since most of my animations are 20 frames or less, only takes 2 minutes.