Having problems understaing aspect ratios

[PlayWithFire]

I am pretty lost with the video i am working on.
Let my try asking the questions as simply as i can. When i view the video, it appears to run at 640x480 and looks normal, but when i take a screenshot it's dimensions are 720x480. And when i try to load the video into GSpot, i get the same dimensions. The screenshot looks stretched to me. I am getting ready to load the videos into DVD Styler, and want make some thumbnails for it first. Here's a a screenshot of GSpot with the information.

[mats.hogberg]

Take your screen shot, and resize to any 4:3 AR like 640x480 and use that as your thumbnail. mpeg2 can have 16:9 or 4:3 AR, but if we talk Video DVD, can have a resolution of:
720 x 480 pixels MPEG2 (Called Full-D1)
704 x 480 pixels MPEG2
352 x 480 pixels MPEG2 (Called Half-D1, same as the CVD Standard)
352 x 240 pixels MPEG2
(Copied from https://www.videohelp.com/dvd)

/Mats

[PlayWithFire]

Ok, i guess i'll just resize it, and try to make the DVD.
Thanks!