Suddenly I couldn’t play YouTube or Flixxy videos in Firefox anymore. It turns out that the latest version of the Adobe Flash Player introduced some new security feature that made things so secure that nothing worked anymore. Oddly enough, I had to disable a setting in Real Player to get things working again.
You need to start Real Player and click the Real Player icon in the top left corner, then select Preferences. Select Download & Recording in the left pane and uncheck Enable Web Download & Recording.