Resolution looks pretty good to me.

Thanks for the comments. Resolution is 640x480 shot on an older consumer camcorder in SD. Can't go back on that now, unfortunately. However, I am working on getting a version up without the clearly visible interlacing and without the letterbox. Coming soon.

When Vimeo encodes in "HD" mode it does a better encoding in terms of bitrate. To get to that mode, you need your video to be over 800 pixels wide. You said you shot with a widescreen SD camcorder, and I can assume it was NTSC. Which means that the playable surface is NOT 720x480, but 874x480. Which is eligible for the "HD" kind of re-encoding here on Vimeo.

So, all you have to do is to export in 1.000 aspect ratio, 874x480 (no letterbox), and with de-interlacing. That would do it.

One day I'll hopefully have access to the original tape again. Until then, I'm working with the file I have. Interlacing should be gone, and the letterbox removed for a resolution of 640x322.