Hi, I have an iMac 5K 2017 with an i7 4.2GHz, 16GB RAM and Radeon Pro 580 graphics running macOS 10.13.6.
My problem is, I have some videos like this that are very high quality (4K, 60fps, HDR, high bitrates etc) that my top spec iMac can't play but my iPhone X can! I have the mpv player...