Ignorant Programmer - OnePageCheckout.cshtml

Hi,
I'm looking at OnePageCheckout.cshtml, and realized I'm stupid :)
Can anyone explain the following:

                <div id="checkout-step-payment-method" class="step a-item" style="display: none;">
                    <form action="" id="co-payment-method-form">
                    <div id="checkout-payment-method-load">
                        @*payment methods content will be loaded here*@ Payment is not required
                    </div>

How are the  payment methods loaded in the commented out section?
I assuming its populated by the public.onepagecheckout.js but I do not clearly see how.

My end result is I was looking into changing the "PayPal Standard" text into a PayPal image (I think it would look better)... but became curious on my search.

Thanks
Rob

...Okay Well I do see its populated from the OpcPaymentMethods.cshtml

Though I'm still confused/interested in how this was called.
(Thinking this is from CheckoutController.cs    testing it now)

Thx,
Rob