Hello,
We are aware of Flash Player crashing issue with the latest FP 15.0.0.152 on Mac and Flash Player team is working to provide a fix soon. Till then, can you please launch the meeting in addin on Mac as the issue only exists when meeting is launched in browser (Flash Player)? You can try different browsers to launch the meeting if you are facing issues launching from Safari (that is if the above mentioned link doesn't help either!)
Thanks
Sameer Puri