There was a thread a while back about using the Network Recording Player in command line mode to convert an .arf to .mp4. However, the example is not complete. The "response from the Webex team" said to use this command:
C:\>"Program Files\WebEx\WebEx\500\nbrplay.exe" -Convert c:\testARFConvert\mp4.cfg
However, the contents of the mp4.cfg file was not specified.
Hoping to get this answered.
First you need to install the Webex network recording player.
Then follow these instructions to convert from ARF to MP4.
Unfortunately, the command line conversion process is unsupported and may be subject to removal from the NBR playback application without notice. This is the likely reason for the referenced content being unavailable today. I do not have a sample cfg file at this time.