It seems that arf to mp4 conversion is mainly related to the export of WebEx web conferencing video recordings (.arf files ) to MPEG-4 video (.mp4 files), something that can be done only using WebEx programs which support export to several multimedia formats - possibly including MP4 format. You can also use WebEx Recording Editor to edit the .arf recording before you convert it to some other format.
If the export to the MP4 format does not work for you for reason, you can always save it as WMV and use any of the available wmv to mp4 converters to get your .mp4 video file.Open ARF file Open MP4 file
A communication software for WebExp platform
Mac version of Cisco media player
A multi-media player for WebEx formats