[wrxtasy]

I have several external HDD drives with my movies stored on them and with the WD device I just plug the HDD into the USB and play.

My question is:

Are there any problems playing 4k HDR content (bluray remuxes/mkv etc) the same way? I do know I would need a powered USB hub or a self powered USB HDD.

Thanks.

You are correct about power requirements.

AMLogic and RPi's, Vero's etc - than use low powered mobile based ARM chipsets can generally only support one 2.5" directly connected hard drive because they simply cannot supply enough USB power. They are not desktop PC.
If you want to use more than one 2.5" HDD reliably at the same time an externally powered USB Hub is required.

3.5" HDD's that are self powered have no issues.

(Excluding 1080p 3D) - the AMLogic S905X, S905D & S912 boxes running OSMC or LibreELEC Kodi Krypton can playback anything you throw at them. If you need software decoded 1080p 10bit H264 aka Hi10P Anime support buy a S912 powered device. It has more CPU ponies vs the rest.