MP4 files are not listed (counted) as videos on Special:TimedMediaHandler.
I currently have one WebM and multiple MP4 videos uploaded, only the Web; file is listed.
In config: $wgTmhEnableMp4Uploads = true;
Versions
MediaWiki 1.33.1
PHP 7.2.24-0ubuntu0.18.04.1 (fpm-fcgi)
TimedMediaHandler 0.6.0