That tutorial is........stupidly complicated for such a simple thing. The side loops are strange. I can't even begin to tell you how to fix it because I don't understand it either.
I use this one: http://www.cosplay.com/showthread.php?t=69336
It's much easier and faster, and easier to understand. It's how I make the waraji I sell as well as my own waraji for Shuuhei, and I love my waraji. They're comfy and don't fall apart.