I've been having this issue since OneUI 4. Sometimes the video plays once and then stops and sometimes it loops. I'm assuming it should loop all the time but in either case it's inconsistent. Happens on both my S22Us.
I only use video lock screens from the themes store and those usually work every time even with the beta. Maybe there's a bug if you're using one from your gallery?
Please erase the device cache using steps below. If issue persists, Please update Samsung members app to latest version from galaxy store and send us an error report from the Samsung member’s app -> Beta Feedback -> Error Reports to help us debug the issue.
Turn off the device.
Press and hold the Volume Up key and the Side key.
When the Android logo displays, release both keys.
An 'Installing system update' message may show briefly before the Android Recovery menu options appear.
Press the Volume down key several times to highlight Wipe cache partition.
Press Side key to select.
Press the Volume down key to highlight Yes, then press the Side key to select.
When the process is complete, Reboot system now is highlighted.
