if AVIs match the output movie - is easy to use as background. If they don't - best way to keep perspective and help stop pixalizing is to put on Square and size and move in your scene. I use bryce to make landscape avi (same size as my movie output in P5 PPP) and have had absolutely no problem but have noted others complaining of pixalization - I havent seen it using same size avi. OK now I am knocking on wood ;-)