We ran into an issue where a valid mp4 video file was being rejected with “Sorry, this file type is not permitted for security reasons.” during upload into the media library. No amount of cajoling could get WordPress to accept the file.
Enter “Lord of the Files” plugin. It not only increases security for uploaded files, it manages to not be fooled by whatever was causing the false positive on our mp4 file.
The funny thing is, we had to look at the name of the plugin about a half a dozen times, because our brains kept telling us the plugin was called “Lord of the Flies” and we couldn’t figure out what that had to do with WordPress’ Media Library. We’re glad we kept staring at it, because we would have missed this excellent plugin. Kudos to the plugin developer for the clever naming.