Shekau posted the video to refute reports of his death, the Nigeria's Channels TV said Wednesday.
Boko Haram, fighting to create an Islamic state in Nigeria, has been blamed for attacks killing more than 2,000 people since 2011.
In the video, the man alleged to be Shekau sits in a jungle environment, commenting on recent events, the BBC said.
In August a spokesman for the Nigerian military said Shekau "died of a gunshot wound in an encounter with the JTF [Nigerian Joint Task Force] troops in one of their camps on June 30."
Sign language interpreter at Mandela service called out as fake on Twitter
Puzzle-maker slips 'Murdoch Is Evil' into Rupert Murdoch's Sunday Telegraph