Retro Dithering effect on Video?

Hi there,

I'm very simply wanting to place a dithering filter on a standard avi/mpeg video track, so that the desired result looks like this, except animated [because it is video]:-

I know how to make the Floyd-Steinberg dithering effect on single images in photoshop, but rather than break down my avi file into loads of single image files, there must be an easier way just as a simple plugin natively within After Effects, or even a plugin I can buy right?

Thanks for your help