We have been able to replicate this issue for our Firefox Version 40 users, if you are having this issue on another browser please do contact us.
This issue has to do with a new Firefox Asynchronous Plugin Initialization that has been implemented in the most current versions and you will have to disable it in order do be able to play the game properly.
We do have a few steps to fix the issue, however if you do not wish to make these changes we recommend you to use a different browser:
1. Open your browser and type about:config and press Enter. Press the "I'll be careful, I promise!"
2. On the second screen do a search for dom.ipc.plugins.asyncInit, the Value should say "true"
3. Double click on top of the name to change the value to false
4. Clear your Cache and you should now be able to play 8 Ball Pool Multiplayer again without any problems!
Thank you for your patience.