I have a 16GB iPad 3rd Gen and tried to rent two HD movies before a flight. One downloaded, taking ~5GB of space, and the other won't begin downloading due to a lack of space.
Is there any way I can take these two HD downloads and downgrade to the SD version without re-buying the content?
No way I know of. You can get SD versions when you purchase an HD movie, but to the best of my knowledge this does not apply to rentals. If you need the SD version, you'll probably have to rent the movie again in that format. Sorry.
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