I found this on a Mac OS site. It allows you to use your screensaver as your desktop background:
- Open the Terminal app.
- Type (all on one line): /System/Library/Frameworks/Screensaver.framework/
Resources/ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine -background &
- Hit enter.
- Terminal will return with the process ID
- If you want to stop the screensaver background, in the Terminal, type kill followed by the proces ID.