Final Cut Pro Square Pixels Question

I have been uploading old SD Mini-DV camera footage exported from Final Cut Express to my Vimeo page. On many of my uploads, there is the warning message that the video does not use square pixels, which could result in a squished-looking image. I only recently noticed that it looks like Vimeo is stretching, not squishing, my videos as a result of this. For instance, a video with dimensions of 640x480 (that's how it captures) is stretched just a little bit wider than that, as well as videos that are 853x480 (those are the two formats in which my camera recorded and how they captured into Final Cut).

While I am aware that my videos do not have square pixels, I guess I am wondering if that's a major problem outside of Vimeo. Final Cut Express, to my knowledge, does not even have an option to change to square pixels (at least in my version) - it simply exports the native pixel image of NTSC - CCIR 601.

Additionally, I have HDV footage that I exported out of Final Cut Pro 7 that has the same issue - the videos are stretched slightly on Vimeo. When I switch to square pixels in FCP for these videos, it makes them look incorrect. Again, I think I have the same question - is there something inherently wrong with these exports because they don't have square pixels? These Final Cut exports are what I consider my "masters," and it makes me nervous to think that they should have been exported using square pixels instead of their native pixel aspect ratio (which, in the case of the HDV footage, is HD 1440x1080).

Any help is greatly appreciated. I am not quite getting the answer I need from the Vimeo forums, and technically this is a Final Cut output question.

Thank you so much.

Jack *****

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