I'm pretty sure Mathew is NOT talking about me.
I'm definitely not talking about Brian.
Actually Brian is a victim of this principle.
The difference between Brian and others is that he gives "samples" on a community basis to give people an idea of who he is and what they can expect. That's a perfectly fine to do from an ethical standpoint and is fair self promotion.
There are others, however, that send out free DVD's to your home in handwritten parcels with a friendly memo attached in order to make you feel that you have a debt to repay. To keep the record straight, I will inform that at some juncture in time someone used Brian's site to create their own forum and gain a customer base for themselves. The reciprocity principle was the tool for someone to do just that.