The wonderful CGPGrey has another explainer video, this time discussing the history of the planets within our solar system, and why certain planets were granted planetary status, and why some were not. If you remember the whole Pluto kerfuffle from a few years ago, you'll enjoy this look at why that happened.
At this point I still think that Pluto is on the outside looking in, but I'm fine with including him on some sort of grandfather clause.
Keith Shaw rounds up the best in geek video in his ITworld.tv blog. Follow Keith on Twitter at @shawkeith. For the latest IT news, analysis and how-tos, follow ITworld on Twitter, Facebook, and Google+.