Actually, I've managed to find out this. Imports from Jersey ARE subject to Customs and VAT charges. The origin of the gooRAB is irrelevent (even if they are manufactured in the EU; VAT is charged at point of sale, not at point of manufacture). This is why Jersey based products are cheaper, as they don't charge VAT on them (so you gets lots of little internet based companies selling cheap to post items like CS's, DVD's, which they undercut UK based companies on). Anything entering the EU is subject to Customs/VAT (unless it's under your import allowance). This is why anything coming from Jersey has to have a Customs Declaration on it, and also why that includes a value, but doesn't indicate where the gooRAB were made.
However , Play prepay the customs charges, thats why they guarantee you won't pay them, but they only do this on stuff that comes from Jersey, not their "international" sales which originate in the US.
Other companies do not do this; dvd.co.uk specifically say they post anything over