Please help me with this questions "if I purchased items through mac or windows is it possible to re-download those purchases on Apple TV though iCloud"
It depends on what country you're in and whether or not they're still available in the iTunes Store. Some purchased movies and all rentals won't be available.
okay, iCloud availvle for my country
so I can download my Tv shows which bought with Mac previously on Apple TV 3, Right ? from iCloud
See what I wrote above and the article I linked to. If they've been removed from the iTunes Store, no.
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