Cant play MP4 Video through Apple Photos

[swandy]

I imported a MP4 video (about 25 minutes long) into the Photos app on my iMac (running Big Sur). The Photos can play the video fine on my iMac but refuses to play it ("unsupported format) on both my iPhone 12 and iPad mini 5 (both running the latest versions of iOS 14.4 and iPadOS 14.4. Any suggestions?

 

[chabig]

The video is encoded in an unsupported format. VLC will probably play the video.