It's not like you need any reason to rush out and grab a free download of Portal, Joystiq's 2007 game of the year, which is now also available on the Mac. We're just going to assume you already have downloaded it but are somehow unable to play it right now. As such, you'd probably like to watch a cute video about Portal in order to pass the time until you can play it. It turns out we happen to have one. Enjoy it after the break.