How does Build A Niche Store & eBay work together.?

Maybe I am just dense but how do you make money on other peoples auctions? I have been looking for a way to start an online business and came across this http://buildanichestore.org.uk . They claim you can make money off promoting eBay's auctions, is this a scam? Does eBay really need help in promoting auctions? Seems strange to me as everyone already knows about eBay. Thoughts please.