I'm pretty sure the the pixels are 1.33 because I've been able export in other programs with the following results: 1.0 pixels yields a 4:3 aspect ratio that looks squished and 1.33 pixels yields a 16:9 ratio that looks correct.
With Premiere, I've tried the following settings:
- NTSC DVD Standard (720x480)
- NTSC DVD Widescreen (720x480) (1.212 pixel ratio)
- MPEG2 1440x1080i 30 (1.33 pixel ratio)
- DV NTSC Standard (720x480)
- DV NTSC Widescreen (720x480) (1.212 pixel ratio)
- HD 1080i (1440x1080) (1.33 pixel)
- HD 720p (1280X720) (1.33 pixel)
- LAN (640x720)
Some others I can't remember at the moment. The widescreen settings letterbox both top and bottom, so again, I'm pretty sure that's the right dimension.