While searching YouTube, as you do, I stumbled upon a Portal 2 music video. I was utterly amazed at the quality and effort that is shown in these videos. The person who made these clearly loves Portal 2 and spent a long time on these. While watching at first I had to check that this wasn't an official video done by Valve, it just looks stunning.
The person who did it also put up a bunch of videos on how he made it, which I also recommend as its very interesting to anybody who is into this kind of thing. Watching it in the end though has just made me want to go and play Portal 2 again, which I may just go and do. There are also a few other videos by this guy that spoof other songs that you should check out.
Dug a little deeper and found this one.