Yes, the camera is looking for a 5V DC source, however as I alluded to in the article, getting a clean 5V out of standard batteries without building a step-up or regulator of some kind isn't easy. To keep the article simple and on-topic, I decided to risk it by slightly over-volting the camera.
I've run the cam at 6V for many hours without any ill effects, but perhaps I've just gotten lucky. If you're concerned about the voltage, you could build or buy something like this from SparkFun:
http://www.sparkfun.com/commerce/product_info.php?products_id=8248
Brian