We're currently looking into releasing our own app for allowing you to use our countdowns as a screensaver, but in the meantime there are 3rd party apps that will let you set any web page as a screensaver. Sorry, but we can't support this software if something goes wrong.
Here are some options for Mac OS X:
- WebView Screensaver: https://github.com/liquidx/webviewscreensaver
- WebSaver: https://github.com/tlrobinson/WebSaver
- WebSaver: http://www.brock-family.org/gavin/macosx/websaver.html