4K content from Apple can be streamed, but not downloaded directly on a device according to Apple: customers can download a local copy of an HD movie, and on occasion, HD movies that support HDR and Dolby Vision, but 4K movies are not available for download and thus can't be watched without an internet connection. It's not clear why Apple is not allowing customers to download 4K content onto their devices, but it could potentially be a licensing issue. Apple is providing 4K content at the same price as HD content, though movie studios were rumored to want to charge more. It's also possible it's a local storage issue, as 4K movies have large file sizes. To stream 4K content to the new Apple TV 4K, Apple recommends a minimum speed of 25Mb/s, according to the support document. If an internet connection isn't fast enough, Apple will downscale the video quality.