This is an awesome hack, but I gotta point out that the price point on "real" SV he's using is off. It's $400+ if you buy a Sous Vide Supreme. But you can also buy a $40 rice cooker (which is a multitasker) and a $130 PID controller from Auber Instruments.
The only downside to the beer cooler hack, besides the fact that it's not precise enough to do eggs, is that it won't work over very long cook times. It looks like it'll kill on steaks, but it isn't going to work for medium rare short ribs.
More Hacker News on Sous Vide, another topic I seriously will not shut up about, is here: