The group say all of the girls have been converted to Islam and there were all shown wearing headscarfs on the video.
Their suspected leader, Abubakar Shekau also added that they would release the girls as an exchange for militant prisoners being freed.
Boko Haram took the 276 girls from their school In Nigeria on April 14. Almost a month later, there have been reported sightings of the girls in various locations - which have all been passed onto the military.
Shekau tells the camera in the video that they have 'liberated' the schoolgirls, adding: 'These girls have become Muslims. They are Muslims.'
And despite the Archbishop of Canterbury today urging the Nigerian government to negotiate with the militants for the girls' safe return, they say they have no intention of paying a ransom for the children, because 'the sale of human beings is a crime against humanity.'
Even the father of one of the kidnapped has said he does not want to government to release Boko Haram members in exchange for the children, stating: 'It's not right. They'll do it again.'
Boko Haram means 'Western Education is forbidden' and they objected to the girls attending school rather than getting married.
So far a number of celebrities have backed the campaign to bring back the girls, including Angelina Jolie, David Cameron, Barack Obama and Beyonce.