A bunch of Bluray players can do 4k output for Netflix so can probably do the playback. Whether they can playback from a disc is another question.
https://help.netflix.com/en/node/13444

VLC supports 4k.

Am I missing something? You're asking how to playback 4K content?

I'd be surprised if a 4K TV couldn't playback from USB. It's the main way they demo them.
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Christian
#40104192 120Gb (no longer in my E36 M3, won't fit the E46 M3)