Jason, sorry for the delay in replying. This effort took a back seat to a more pressing site requirement. But finally got a chance to give your suggestion a try and tried to access the Webinar using Firefox 35.0.1 and I'm seeing exactly the same issue See attached screenshots for the messages I receive. Let me know if you need any other info. thanks!
I'm on a Win 7 Pro machine
I also just downloaded Adobe's Acrobat Connect Add-in v 8 & 9 and installed those but that didn't help :-/