Having the same problem. I am running windows 8.1, everything else the same.
Plugin keeps crashing over and over again.
Tried every solution posted about this problem. Nothing works. Problem started today.
problem solved. Downloaded beta version of plugin released today. Pinned it to task bar. Quit firefox. Restarted computer. Installed beta plugin. Started firefox. Now videos play.
Download Flash Player 12 Beta
Adobe® Flash® Player 12 drives innovation for rich, engaging digital experiences with new features for cross-platform browser-based viewing of expressive rich internet applications, content, and videos across devices. This beta release provides access to the Flash Player 12 runtime for Mac OS and Windows desktop environments.
Version Beta Date Jan 21, 2014 See release notes
Thanks for the quick response. After two tries, it worked. Videos now run on Firefox.