Broadcasters from non-Commonwealth nations pay 1,500 pounds per minute for footage of the chat. And, all profits go to good causes through the Foundation of Prince William and Prince Harry -- set up last year, 'The Sun' reported.
The second-in-line to the British throne and Kate, both 28, got engaged this October and are to tie the knot in April next year.
"William and Catherine were aware that there was likely to be a demand for the interview and broadcasters would be prepared to pay for it. They saw it as an opportunity to make money for the causes that are close to their hearts," a St James's Palace source was quoted as saying.
The 20-minute recording of Wills and his bride has huge value as it was the first time Kate had spoken in public. Access to the interview was free for 24 hours after it aired. Since then non-Commonwealth broadcasters have to pay a licensing fee.
A source at ITN, which owns the November 16 footage, said: "There's no fixed rate but it's working out on average at around 1,500 pounds every minute. It's selling well, as you would expect, so the charities are really benefiting from it.