The footage shows a man resembling Kim Jong-chul visiting the Royal Albert Hall.
Kim Jong-chul has previously been seen attending Clapton concerts abroad.
One North Korea observer said the man in the footage did appear to be Kim Jong-un, who was taken out of the leadership succession several years ago.
Video filmed by a Japanese television network on May 20 shows a car arriving outside the venue in west London, and a woman wearing a green leather jacket and sunglasses emerging from inside.
Cameras follow her briefly before another similar-looking man, dressed in identical clothes, also walks out of the car.
He is asked a number of questions by journalists but does not speak. Several minders surround him, and they push journalists and cameras away from the man.
The same visitors were seen at a second Eric Clapton concert in the same venue on May 21.
Kim Jong-chul has attended Eric Clapton concerts in Germany in 2006 and Singapore in 2011.
The South Korean news agency Yonhap said that the man stayed at the Chelsea Harbour Hotel in west London, where rooms can cost more than £2,100 ($3,290) a night.
He was due to board a flight to Moscow on May 22, Yonhap said.
Kim Jong-chul is the oldest child of the fourth wife of former ruler Kim Jong-il, and is 33 years old.
Like his full brother Kim Jong-un, Kim Jong-chul was educated in Switzerland before returning to North Korea.
Kim Jong-chul plays an important support role for his brother. At one point, he worked in North Korea’s propaganda department.
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