Why are both sides fullscreen when one side is supposed to be widescreen

Many DVD's are labeled as having widescreen (16:9) format video on one side and standard (4:3) on the other. If you think both sides are the same, you're probably seeing uncompressed 16:9 on the widescreen side. It may look like 4:3 full-frame, but if you look carefully you'll discover that the picture is horizontally compressed. The problem is that your player has been set for a widescreen TV. See 1.22 for details.