I have to admit that I never quite understood the whole 720x576 being 4:3 AR with non-square pixels story...but hey, they make 1024x768 Plasma TV's with a 16/9 AR, so I assumed that non-square pixels were an acceptable practice in the video world.
So how do you know the actual AR of a 720x576 FS stream then? Are you saying that 720x576 FS is not/never meant to be watched with a 4:3 AR? It sure looked OK to me