I think i udnerstand it but im not sure. So basically if i wanted to buy a phat from someone on sythe and we used a MM, both parties would give our goods to the MM, and he would give them to the other person?
Not always, the way I do it is a little different.
I would go on the person with the phats account and verify it. After I secure the account, I'll get the other person to send the money, once the money has been received I'll give them the phat.