A simpler alternative to xwinwrap's confusing commands, this unofficial chooser panel currently supports both xscreensavers and videos (through mplayer). It offers a few options (opacity and whether to use nice) and starts xwinwrap with a screensaver or video of choice (+ optional arguments). If the chosen screensaver allows the "--speed" option, it will detect that and enable the slider (this is not always reliable). A few example presets are included, but it's easy to create your own new effects and save them to use again. For now, execute it in the directory. It requires xscreensaver and xwinwrap, and mplayer for video support. Homepage: http://code.google.com/p/gwinwrap/