This is a piano piece called "Sparks," I think. Don't remember where I got it though. This is an example of a "hidden" plug-in. As far as I know, Netscape doesn't support hidden plug-ins yet (although they have an API for it.). However, QT MIDI Plugin can simulate a hidden plug-in for you! If you set the Height and Width of the plugin to anything less than or equal to 2, it will be a hidden plugin, and you won't see anything on the screen.
When you are done on this page, click here to view some embedded plug-ins.