Thanks for sending me the video. I’ve created a layout with your M4V file and it is playing without issue in my Xibo for Linux player running on Ubuntu 18.04.5. Below is a screenshot showing the video playing and the status page so you can see that I’m running the latest version of the linux player:
I have not tried ubuntu 20.04 with the video yet but will again update this post once I have. In the meantime I would recommend making sure that your Linux installation is up to date and you are using the latest version of Xibo for Linux, which is 1.8 R6.
Many Thanks.