Firefox on OSX

Am I the only one in the past few months, since one of these “automatic” upgrades from Firefox or WordPress, that this VideoJS plugin always displays Mime Errors?

Every Mac I try with Firefox on my site gets “No Video with Supported Format and MIME Type Found”. I saw some .HTAccess here in the threads, but that didn’t seem to help my own problem.

All other combinations seems to work fine.

https://wordpress.org/plugins/videojs-html5-video-player-for-wordpress/