If you have an original .arf version of this file that won't play, you can use the Webex Recording Converter to turn it into a standard MP4.
If you are trying to create an AR experience with this file, tools like Adobe Express can help ensure the MP4 is optimized for web-based AR triggers. AR 00103b mp4
Most AR platforms recommend avoiding full-frame pure black at the start to prevent "blank" triggers. How to Manage the File If you have an original
Must use even numbers for width and height (e.g., 1280x720). Constraints: High Profile, not exceeding Level 5.2. 1280x720). Constraints: High Profile
If it is a standard MP4, it should open in VLC, Windows Media Player, or QuickTime.