If this were my win, I don't think I'd cancel the paypal transaction - that would leave you open to negative feedback, however I would try to email the seller again and maybe check out the support at paypal. If the email is not registered that means the person actually DOES NOT have an account yet, he may be in the process of setting up an account.
If the seller is not VERIFIED just means he hasn't linked an account and unconfirmed is the address thing.
I guess I'd make sure before I cancelled anything. You could also try contacting safe harbor at ebay - they helped me once when I was in a bind.
Tell Safe Harbor you are worried that you'll get negative fb if you cancel the payment and that you haven't heard from the seller. They may email him for you as well.
Since it was only paid for on the 19th, which means it is entirely possible the item wasn't even mailed until the 22nd or later I wouldn't worry about it too much, especially if the items is coming a long way, it may have been sent parcel post which sometimes takes up to 10 days anyway.
I don't usually get concerned until it's well past a month if I don't get something.
Keep us posted on what happens..