You do realize that when played back, a 720x480 (non-square, rectangular) pixels 4:3 AR flagged video will display as 640x480 (square) pixels?
My advice is correct for 720x480 resolution video that is using NON-SQUARE pixels. When played back on proper equipment/software and assuming the video is correctly flagged, it will either be displayed with square pixels as 640x480 if 4:3 or 853/848x480 if 16:9.
http://www.animemusicvideos.org/guides/ ... atios.html
I assumed the original video source was either 720x480 (rectangular pixels, 0.9 AR, anamorphic) video or 853/848x480 (square pixels, 1.0 AR) video at 16:9 aspect ratio. 608x320 (1.90:1 width-to-height ratio) is an usual resolution/aspect ratio for anime. Most widescreen anime are 16:9 and with square pixels have 853/848x480 resolution and a 1.78:1 width-to-height ratio. Some newer anime movies may be 1.85:1 AR while the majority of older movies are just 4:3 (1.33:1) AR, same as TV shows. Another AR you may run into is 5:3 (1.66:1).
Here's an old thread with some nice illustrative images of the difference between PAR (pixel aspect ratio, i.e. 720x480) and DAR (display aspect ratio, i.e. 4:3) and the importance of proper AR flags:
http://www.animemusicvideos.org/phpBB/v ... hp?t=65156
P.S. this reply needs a re-write for better clarity, but I'm tired and it's late.