Kano - Boko Haram has claimed the 219 schoolgirls it kidnapped in Nigeria earlier this year have converted to Islam and have been married.
The Islamist group's leader, Abubakar Shekau, also denied claims by Nigeria's government that it had agreed to a ceasefire and apparently ruled out future talks.
In addition, Shekau said the Islamists were holding a German national, who was kidnapped in Adamawa state in northeast Nigeria in July.
The schoolgirls were kidnapped from the remote northeast town of Chibok in Borno state in April, raising global awareness about the group whose five-year insurgency in northern Nigeria has claimed an estimated 13 000 lives.
The new video, obtained by AFP on Friday, comes after a surprise announcement by the Nigerian military and presidency on 17 October that a deal had been reached with the militants to end hostilities and return the children.
There was immediate scepticism about both claims. Previous ceasefires have proved fruitless and there is little trust in the influence of the purported Boko Haram envoy, Danladi Ahmadu.
Violence - and renewed kidnappings - have continued unabated since the announcement, including a triple bombing of a bus station in the northern city of Gombe on Friday that killed at least eight.
Nigeria's government maintains that talks are ongoing in the Chadian capital, Ndjamena.
But Shekau, speaking in Hausa, dressed in military fatigues and boots with a black turban, and flanked by 15 armed fighters, said: "We have not made ceasefire with anyone.
"We did not negotiate with anyone... It's a lie. It's a lie. We will not negotiate. What is our business with negotiation? Allah said we should not."
He also said he did not know Danladi.
Shekau previously threatened to sell the girls as slave brides and also suggested he would be prepared to release them in exchange for Boko Haram prisoners.
Human Rights Watch said in a report published this week that Boko Haram was holding upwards of 500 women and young girls and that forced marriage was commonplace in the militant camps.