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:
cd ~
wget http://support.webex.com/supportutilities/nbr2mp4.tar
tar -xvf nbr2mp4.tar ./
chmod +x ./nbr2mp4.sh
./nbr2mp4.sh
cd nbr2_mp4
./nbr2mp4 SOURCE [MP4_VERZEICHNIS] [FPS]
Enjoy!