I think it has to do with AAC encoding. Like I said if you reencode it as h264 it displays fine on the problem browsers.
chrome issue. i can see it fine on firefox and samsung browser nostr:npub13v68j9479je6h958e84h32xs2gjvq3duuk6pd0w4q95evh4s73wqk2hy07 might be worth it to look into this further
Discussion
food for thought. ill do some testing today
stackoverflow.com/questions/60882500/html5-video-player-some-mp4-files-not-playing-chrome