Glad it is working for you. Still not working for me after updating to 14.1 in QT. Do you mean that if there is audio the video will not play at all? I tried muting the audio but the video still did not play.Good news, mpg files now play in Sonoma 14.1 Final build.
Bad news, if those mpgs have audio, it just doesn't play (no sound) in QT Player.
They play fine in Movist and VLC though.
As the same behaviour was reported in Monterey and Ventura, you could say that macOS isSonoma is crap obviously
They fixed QT in Sonoma 14.2, now it plays mpg video.I'm having the same issue. MPEG files that played fine in Ventura will now only play the video portion without the audio after updating to 14.1. I had to use Handbrake to re-encode all the videos embedded into my Keynote presentations.