I don't think the seller would risk getting negative feedback for a 6 quid dvd.
try use the "ask seller a question" link in the item page, seller might use different emails.
unlike normal delivery, seller has to go to the postoffice for recoreded letter, which might be a delay, and sometimes recorded are slower than normal.
go check the seller's other activities, if there isn't any, he might be out of the country
