i believe there is more of a simpler way of doing it, basically if you click on one of those porno links if redirectsyou straight away to the log in page, if you try putting in a fake password and username it wont take it so i dont know how they did that, however the page was created by them so as soon as you enter a correct ebay username and password it sends the details to a server where they can access the information, i tried creating something like that for msn to snag peoples msn usernames and passwords but i couldnt get it to work properly.
