If you're talking about mine, I'm not quite sure
What I THINK I did though was follow cjmcguinness's steps above for creating a a 4x4 grid...ish.
I used 4 colors, and made a grid that somewhat came close to the size of my tiles, while not having half squares hanging off the sides. I then followed his motion blurring directions.
After that, I think I simply duplicated that layer, merged the two "Color Grid" layers down, and then finally set the composite layer's blend mode to Color Burn.
... I think.
But thanks for the compliments! That really made my day!