It seems that the Flash 11.3 roll out has not gone smooth for Firefox users, quite the opposite. Flash 11.3 introduces the Flash sandbox, or protected mode, to Firefox but it seems that the security feature is causing problems in some cases. Add-ons and other plugins which enable users to record Flash videos are at least part of the problem.Both Adobe and Mozilla are investigating the issue and there's no proper fix for all the problems just yet, but both companies have released several workarounds. The problem only affects Windows Vista and 7 users.
Upgrade to Firefox 13.0.1Users are reporting that videos don't play and in some cases that there are even crashes. These should have been fixed with the latest Firefox 13.0.1 update, which you should definitely get, but the rest of the issues are still there.
You can take several steps if you are affected. If video doesn't play, the problem is most likely caused by another plugin or add-on.
RealPlayer Browser Record has been blocked by Mozilla, but there's an alternative solutionMozilla has already blocked the RealPlayer Browser Record plugin since it interfered with Flash's normal operation. The plugin will be automatically blocked in Firefox, but you can re-enable it if you want to. If you're having problems, it's best to leave it disabled until Mozilla lifts the block.
Alternatively, you can disable the video downloading feature in the RealPlayer plugin. Launch RealPlayer, go to Preferences > Download & Recording and uncheck "Enable Web Download & Recording for these installed browsers" to do this.