Isn't instant transfers done by lowering the required confirmations, and in return increasing the risk of bogus transactions?
Well the initial deposit to my site I would require 3 confirmations to be safe, otherwise double spends can occur. But once they have deposited to the virtual balance, well transactions within the site are instant. Think of it like this, Paypal is to USD fiat as this site could work along side bitcoin.
A few other pluses to this could be minimizing constant blockchain transactions.