If you wish to make a screensaver from a flash file then just follow the steps. Download the free software (4.98 mb) from http://www.goldshell.com/flashforge/main.htm  . Then you will be able to convert a flash file into screensaver.If you want to make screensaver from a video file  then convert the video file into flash (SWF format). You can do it by a free software named Video to Flash Converter. You can download this software from  www.dvdvideosoft.com