LED Throwies are an inexpensive way to add color to any ferromagnetic surface in your neighborhood. Each throwie consists of an LED, lithium battery and strong magnet taped together. If you make enough of them, the results are interesting. Of course scattering clumps of lithium batteries, LEDs and magnets all over the place isn't the most ecologically friendly thing to do but it looks like fun. Watch the video.
I think the music choice in the video was intended as a nod to the Sony Bravia Bouncy Balls commercial. It's José González doing a cover of Heartbeats. Nice.