djrudyg Nick, are any additional plug-ins needed to be installed on a Macbook to be able to play 4K resolution mp4 files?
Nick No, you should be able to play them within MixEmergency already, provided that your computer is up to the task of decoding multiple 4K video streams in realtime.
djrudyg Nick, some videos downloaded from YouTube use the av01 codec instead of the H.264 codec that Quicktime recognizes. What can be done in those type of situations?
Nick Those videos would need to be converted to a format supported by MixEmergency (e.g. H.264, HEVC, etc).