Yes, all end users need to have the Microsoft IE version of the Adobe Flash player installed for running screensavers generated with Swiff Saver.

The required Flash Player version depends on the Flash movie used to create the screensaver. For example a Flash 4 movie will require Flash player version 4 or later. Running screensavers on platforms where only the Netscape version of the Adobe Flash player is installed will fail. The Flash Player ActiveX/COM object must be installed on the end user system. The Flash Player ActiveX/COM object comes with the Adobe Flash Player for Microsoft Internet Explorer.

According to the Adobe Survey, more than 99% of Web users can experience Adobe Flash content without having to download and install a player.