Codes from 4K Blu-Ray discs should redeem as follow:
Warner Bros:
Flixster: Redeems UHD
VUDU: Redeems UHD (only if available in their catalog)
Lionsgate:
Flixster: Redeems UHD
Redeems HD elsewhere
Universal:
Flixster: Redeems UHD
VUDU: Redeems UHD
Universal Studios: Redeems UHD
Sony:
Sony...