OK. I'm getting there. See
BOLD for quick answer)
The 5:4 aspect ratio is the ratio of the number of pixels. 720:576 = 5:4.
So, when we "keep original size" AND use square pixels (without "stretch to fill") the image we produce is 720 x 576 SQUARE pixels. This image has a black band top & bottom (letterboxing) so that the visible image is the correct aspect ration (4:3)
If we do the same but "stretch video ...do not letterbox" then everything is stretched vertically. Not what we want.
We cannot specify that we want the pixels to have the same aspect ratio that they do in DV-AVI (1.066666:1) but we
can and should specify the output size.
Choose 640x480 and away you go. (My V9Pro has a built-in template "3Mbps Video" which does the job)
Now in actual fact, if you don't choose "stretch to fil..." there will STILL be a slight letterbox effect. I cannot figure this as 720 x 576 multiplied by the Pixel Aspect Ratio of 1.067:1 actually does work out at 4:3 (or 640:480)
My best guess at the moment is that although the real PAR is 1.066:1 some sort of standards use 1.09 or 1.0925:1 which I think relates to 704 x 576!
Pixel_aspect_ratio
but this is way over my head and we're close enough.
Also, if you're doing this for the web, you should really deinterlace or any fast movement will show up as "combing".
In project properties select a de-interlace method of interpolate or blur (whichever looks best).