Flick of a switch controls this Earth Hour ad

The World Wildlife Fund teamed up with Hot Chip to create this cool online ad for Earth Hour. It's actually two videos in one—a "light" version and a "dark" version. The one that plays for you depends on the amount of light your webcam is picking up. (Your room needs to be very dark to play the dark version, so hold your hand over the webcam if you have to.) If you're still rocking a webcam-less computer from 2003, you can check out an alternate version over on YouTube, where you toggle between light and dark using a light switch in the upper right.