I can't say that all TVs can playback 4k. Of course there's various encoding methods, containers etc. High bitrates might case problems too. Slow USB drives could even be a weak point.
As I said, I would *expect* any 4k TV with a USB port to be able to playback from a USB drive.
You'll probably find it difficult to get a set combination of codecs, bitrates etc that work on all of them due to the nature of how standard standards end up being.
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Christian
#40104192 120Gb (no longer in my E36 M3, won't fit the E46 M3)