If you have Flash Plugin installed but still can't see an animation, please check the security settings of your internet browsers. For instance Microsoft Internet Explorer requires that ActiveX Controls are enabled in order to display flash-animations. Proceed with care, if you don't know how to adjust security settings, we recommend leaving them as they were or asking advice from a person who's more experienced with computers.

Other solution is checking how you've adjusted your browser to handle different filetypes. Check that .swf -files are set to be run/opened with Macromedia Flash Player.