1280x720 opens as 960x720 in Quicktime Player?

I did not shoot or edit this, but am trying to understand and fix the issue. The footage was shot 720p 24 DVCPro on a HPX170 and imported into Final Cut, edited, and exported. That is the file and info I was given. According to the file properties, the dimensions are 1280x720 and the codec is Linear PCM, H.264.

When I open it in the Quicktime Player, it plays with a squished 4:3 (960x720) aspect ratio, but with Quicktime 7 or VLC Player it plays in the proper 16:9 ratio. Why is that? This is a clip that may need to be given to clients so a solution that doesn't require them to change the actual file or their media player settings is preferable. How can I fix it to open and play properly from the get-go?