Open Letter to the Universe, by Minute Physics, from YouTube.
Simple, entertaining videos explaining what can be rather complex ideas about science. Love it. This is what the Interwebs were made for. Just throw a few cats in there, and you're covered.
And while on the subject of Interweb Science, Dr. Thomas R. Holtz, Jr. has entered the Twitterverse, "mostly for instructional purposes". Dr. Holtz already has a fairly large web presence, so I'm a little concerned his being on Twitter might officially break the internet. But I still recommend following him @TomHoltzPaleo. I'm sure we'll end up seeing some cats there too. Happy Friday!