The Times has the story:
IT WAS not until midway through the live television interview that the BBC interviewer started to grow suspicious. The man whom she believed to be an expert on internet music downloads seemed to know precious little about his subject.Full interview here. The look of sudden horror, followed by a feeling of "Oh, what the hell!" that goes across the guy's face as he realises he is being interviewed live on TV about a subject he know very little about is an object lesson to us all. In the circumstances, I think he performed rather well.
Not only that, but the stocky black man with the strong French accent bore little resemblance to the picture on the expert’s website, which showed a slim white man with blue eyes and blond hair.
Edited to add The bloke who should have been interviewed has given us his side of the story.