Hm, it looks like you're using the PayPal Cart version of our button codes, which unfortunately don't quite work properly anymore due to changes at PayPal's end which we have been unable to work around, so those codes will be removed from the next version of Seller Admin we've been working on.
The standard E-junkie Cart or Buy Now button codes we provide will still allow PayPal checkouts. If you only expect buyers to purchase one item at a time (rather than adding multiple items to an order), and if you don't need to use our cart's tax, shipping or discount calculation, then you could just use our Buy Now button codes for PayPal, which will bypass our cart entirely and take the buyer directly to instant checkout with PayPal, and these will also work with our affiliate system.
As for tutorials, I'm not aware of any video tutorials for affiliates, but this page provides a visual walk-through with screen shots:
BTW, the step mentioned there about searching for an affiliate program would only be relevant if an affiliate were looking to discover new programs they might be interested in joining. If they're interested in a particular merchant's affiliate program, typically they would simply click the sign-up link that merchant had posted to their own site, which should automatically join them to that merchant's program without needing to search for it.