The type of WebEx meeting and desktop recording is .ARF and .WRF, so of course you cannot play it directly. You must use WebEx Recording Editor first to convert it to MP4 and then it could be opened and played on Windows Media Player, VLC or other devices
Step 1 Download and install WebEx Recording Editor.
Step 2 Open "File" and import the ARF file you want onto the interface.
Step 3 Click on "Export to" and choose the format of WMV.
But if your devices only support MP4, AVI or M4V you must use other video converter to finish this job.
For more WebEx conversion you can refer to this article:
http://www.videoconverterfactory.com/tips/wrf-to-mp4.html