You thought that we were done with the "Sorry I'm late" styled adverts by now, right? You should know better, of course we're not! Here's a timely example for Earth Hour. They call it "the first video controlled by a light switch" because you can switch the lights on and off, which is a pretty neat use of the extra features of youtube. For extra cool, they set it up so that you can watch it at the myearthhour.com/lightsoff
site, which would then react to your home lights with some nifty java I presume.
For extra uncool, earth hour usa forgot to take control over their whole domain and some linkspammy page greets you. Oooops.
It still looks like "Sorry I'm late", either way.