See the video has a .mov extension.
Check: Site Admin Menu -> Appearance -> Media Embedding
See if Legacy Media Players has QuickTime Player (the one that would be used for .mov files) checked ... ie, on.
Suggestion: might be time to convert video files with a local app to convert to something more universal ... .mp4's comes to mind as they (supposedly) can be played on smart devices / tablets as well as desktops. If not that, then hosting videos ... like Vimeo, other that is compatible.
Most browser makers are slowing dropping support for media plugins to add to browsers. QuickTime (used most often for .mov files) has issues and even Apple advises to uninstall IF using Windows:
https://blog.trendmicro.com/urgent-call-action-uninstall-quicktime-windows-today/
https://www.us-cert.gov/ncas/alerts/TA16-105A
'spirit of sharing', Ken