Since ARF is a proprietary multimedia format of WebEx Online Meeting, you cannot directly make it work like a normal media to be played on Windows Media Player or any other devices. You must use WebEx built in convert first.
1. Launch WebEx online editor.
2. Go to "file" and choose "export to" WMV.
3. Begin conversion and extract the wmv video,
4. Find another video converter to convert the WMV file to other common formats like MP4 and AVI.
When I first try playing ARF i had no idea as well. Maybe you can read
http://www.videoconverterfactory.com...rf-player.html which clearly described how to play ARF file.