The six-minute video shows two men with their arms tied to their backs. They are made to face the camera on their knees, with another man towering over one of them brandishing a knife.
The knife-wielding man reaches toward the throat of one of the kneeling men, then the video switches scenes to show what appear to be the bloody severed heads of the two men placed on their headless bodies.
The SITE Intelligence group, which monitors extremist activities, released a translated transcript from the video, including what SITE called an "interrogation" of one of the two men. The man identifies himself as a farmer from the Nigerian town of Baga. He says he was told by a policeman that if he provided information about "the residents who live in here ... I will become rich and never go back to be a farmer again."
The apparent beheadings then follow on the video. SITE said the video, which included Arabic, English and French subtitles, was posted online via Twitter and "borrows certain elements from productions" of beheadings by ISIS.
The video was posted by the media division of Boko Haram, SITE said.
Violent beheading videos
Although this is the first purported beheading video Boko Haram posted online. the group has previously issued more detailed and extremely violent beheading videos directly to journalists through intermediaries. Unlike the video posted Monday, previous ones have shown the actual decapitations.
In October 2014, Boko Haram handed out a 10-minute video showing the decapitation of a Nigerian military pilot the group said it had seized a month earlier after shooting down his fighter jet during a mission against Boko Haram in northeast Nigeria.
In April 2014, the Islamist group released 16-minute video showing what it said was the beheading of a soldier its fighters captured in a battle in Sambisa forest, the group's main enclave.
In February 2014, another video showing the beheading of an alleged informant who led the military to a Boko Haram camp in Sambisa forest during an offensive was issued by the group.
And in February 2010, Boko Haram released a 12-minute video in which two policemen were beheaded in an undisclosed location.
Those videos all ended with a speech from an "executioner" warning that the group would carry out similar punishment for anyone it captures supporting the Nigerian government against it.
Taking on the ISIS style
Observers of Boko Haram, which has inflicted years of terror on northern Nigeria, note that its actions in the past six months have frequently mimicked those of ISIS -- from punishments such as stoning and beheading of its victims to taking territory and an increasingly sophisticated use of social media that's very much in the ISIS "style."
Jacob Zenn, who follows Boko Haram's operations and propaganda closely, recently told CNN, "It's clear Boko Haram is leaning toward ISIS in terms of doctrine, ideology and an emphasis on holding territory after operations."
In terms of ideology, Boko Haram's leader, Abubakar Shekau, has said that kidnappings and hostage-taking are approved in the Quran, a claim ISIS also makes.
"Our hostages are Christians or corrupted Muslims who follow the Christian way," he said last year, referring to schoolgirls kidnapped in Chibok, Nigeria, most of whom remain missing. ISIS later referred to the Chibok abductions in its kidnapping of hundreds of Yazidi women and girls.
Zenn and other analysts point out that recent Boko Haram videos have resembled the polished media productions of ISIS. Zenn notes they "have the same choreography and lens angles as ISIS."
Boko Haram has begun using ISIS symbolism in its media productions and operations. The Nigerian press noted with alarm last July that Boko Haram militants had been seen raising ISIS' rayat al-uqab flag along the Nigerian-Cameroon border. Recent videos have featured the same flag.