Reminder: Apple says it's only streaming 4K iTunes movies, not offering downloads
People wanting to upgrade their desktop iTunes movie purchases to 4K are out of luck -- Apple is only streaming video in that resolution, not offering downloads, according to an official support document.

"You can download a local copy of an HD movie, and you might be able to download HDR and Dolby Vision versions, but you can't download a 4K version," Apple says. The same webpage recommends at least 25 megabits per second of bandwidth for 4K streaming, and notes that falling below this may automatically switch users to 1080p or lower.
It's possible to stream locally-imported 4K video from one Mac to another via iTunes, AppleInsider can confirm if properly encoded with a tool like Handbrake. So, the Apple TV and iTunes itself is capable of performing the feat.
The situation is likely because of deals negotiated with most major Hollywood studios, which mean that people buying iTunes titles get 4K on the Apple TV at no extra cost. Limiting the extra resolution to streaming could be a way of deterring piracy, and/or keeping Blu-ray disc sales alive.
Additionally, the Apple TV won't stream YouTube videos in 4K, and is currently missing support for Dolby Atmos surround sound, though that is said to be arriving at some point later in a software update.

"You can download a local copy of an HD movie, and you might be able to download HDR and Dolby Vision versions, but you can't download a 4K version," Apple says. The same webpage recommends at least 25 megabits per second of bandwidth for 4K streaming, and notes that falling below this may automatically switch users to 1080p or lower.
It's possible to stream locally-imported 4K video from one Mac to another via iTunes, AppleInsider can confirm if properly encoded with a tool like Handbrake. So, the Apple TV and iTunes itself is capable of performing the feat.
The situation is likely because of deals negotiated with most major Hollywood studios, which mean that people buying iTunes titles get 4K on the Apple TV at no extra cost. Limiting the extra resolution to streaming could be a way of deterring piracy, and/or keeping Blu-ray disc sales alive.
Additionally, the Apple TV won't stream YouTube videos in 4K, and is currently missing support for Dolby Atmos surround sound, though that is said to be arriving at some point later in a software update.
Comments
Also it's not the most carbon friendly approach. Content Distribution Networks are fueled by datacenters which are often "fueled" by energy sources that aren't so clean. I'm a bit dismayed that a company that prides itself on not using non-recyclable materials is promoting a carbon unfriendly approach to video video disty.
I'm going to pick up a Nvidia Shield TV and see how that works along with a ATV 4K. I'm feeling too constrained with streamers and this "Just stream everything" when my fastest network at home is my LAN.
So people buy the movie on DVD, and now that it's out on Blue-Ray, they magically expect the studios to give it to them for free? There is nothing to read here.
I'm not sure I buy the carbon footprint here... it's much less than the old days of stamping-out a billion DVD's on plastic, and VHS videotapes back in the day. You're watching the 4K movie either on your TV, or computer, or both... so you're burning electricity either way, and the datacenter still remain on and running whether people stream movies or not.
I routinely exceeded the Xfinity 1TB limit so now I'm paying the extra $50 for unlimited. 4K streaming shouldn't be a problem.
I'm happy that the Apple TV 4K exceeded preorder expectations. I'm glad I ordered one from Best Buy. None of the stores in my area has them other than a few 32g models.
The generation of Electricity in its entirety contributes more carbon than our vehicle emissions. Data centers are getting cleaner thanks to solar and hydroelectric. The first thing I do in every new home is replace low efficiency appliances and lighting. The wife and I are looking at Solar for our roof.
Our children have to clean up the trash the former generation leaves. I’m trying to keep that mess as small as possible
4K from Apple is H.265 now.
https://www.apple.com/environment/
Before you start, No I'm not of the belief Apple is being is being dishonest either, What you think "powered by" and what business means when they say it are two different definitions. You just have to read up to understand what it means.
Apple absolutely deserves kudos for championing wind farms, solar and other renewable energy sources, they lead by example and with their own pocketbook. They are also far better than some of their other tech brethren in this regard (looking at you Amazon)...but heir North Carolina data center is one of the examples of where what is said is not what you're hearing. In truth their North Carolina power operations are powered by Duke Energy, a producer who depends primarily on coal and nuclear and that's what is sent to their Maidenhead center. Purchasing and/or trading in Green credits allow them to claim 100% renewable.
I don't know if you'll bother to read this Forbes link which explains it (and which I would agree upfront comes off as aggressively and unnecessarily harsh on Apple so you'll have to look past it) but it's here if you want to understand the difference between the claim and what you thought Apple was saying.
EDIT: I'm deleting that link to prevent a needless distraction from the thread topic. If you want to separate the wheat from the chaff to understand what an enterprise claiming to be using "100% renewable" sources really means and how it's accomplished it will be easy enough to look for yourself.