Quicktime Pro may do it. That's cheap.
Just about any video editor will do it if you set up the project with the proper dimensions and then rotate the imported video.
The gotcha is that the compression math and color spacing usually, but not always, works differently on the horizontal and vertical axis so when you re render in the new aspect you may see some noticeable artifacts pop out that were masked effectively in the initial file.
There are probably some free solutions... I have existing workflows so I don't know much about all that is available.
Hopefully some one will offer a great idea.
best regards,
mike
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