Im looking for that too, but I think you guys didnt get the main point (or I didnt hehe).
He wants to hide his referer bcoz it kind scares people... I mean, when they click in your affiliate link and land in the next page they notice a username in the url.... it sux ... Im pretty sure that alone raise a few eyeballs. Even more when people think you were just trying to help them (by reviewing a product, or writing an article you know the drill hehe) and instead you were 'just tricking people' to click in your link (which is kinda true ;p ).