Some media players or browsers may have hardware acceleration enabled, which can cause playback issues. Disable it and see if it resolves the problem.
Verify that your device supports the AV4 format. Some devices may require additional software or updates to play AV4 videos. av4 videos us fix
Clearing cache and cookies can sometimes resolve playback issues. Try clearing your browser's cache and cookies or uninstalling and reinstalling the media player. Some media players or browsers may have hardware