The answer I've seen most often on this forum and that make sense to me is this:
You do not need an internet connection to view the downloaded rental; HOWEVER, you do need an internet connection when you start viewing the rental for the first time, so the 24 hour clock can be started.
So you could just watch the first few seconds while you have a connection, and then you have 24 hours to complete viewing the movie, all of which you can do with no commection.
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