The easiest way you can watch webex recordings on Linux is by converting them to mp4 using the NBR2MP4 Converter supplied by webex.
Here are the steps:
tar -xvf nbr2mp4.tar ./
chmod +x ./nbr2mp4.sh
./nbr2mp4 SOURCE [MP4_VERZEICHNIS] [FPS]
Usage: ./nbr2mp4 SOURCE [MP4_DIRECTORY] [FPS]
SOURCE: The name of the source Advanced Recording Format file (.arf)
that you want to convert. Specify a path name if the file is in a
directory other than the current directory.
MP4_DIRECTORY: The directory for the MP4 output file. If MP4_DIRECTORY
is not specified, the MP4 output file will be generated in the same
directory as the SOURCE file.
FPS: The number of frames per second, which should be between 3 and 10,
default = 5.