That URL would be the deprecated "PayPal Cart" version of our button code. Those buttons no longer work properly in many regards (including the Continue Shopping button's behavior) due to recent changes at PayPal's end that we have been unable to work around, so we are removing that version of button codes from the next version of Seller Admin.
We recommend using the standard E-junkie Shopping Cart button codes from your Seller Admin, which provides full support for all our features and will show buyers a PayPal checkout button in the E-junkie cart. You may be able to convert E-junkie's old PayPal Cart button codes into E-junkie Cart buttons by adding &ejc=2 to your buttons' href= URLs, like so:
However, that would not give you our nice, overlay-style cart display "inside" your page, which you would get by using the complete E-junkie Add to Cart and View Cart button code from Seller Admin (you'd only need one View Cart per page):