The 17-minute video shows some 100 girls wearing full veils praying at an undisclosed rural location, according to AFP news agency, which obtained the film.
AFP says the leader of the Islamist Boko Haram group, Abubakar Shekau, alleges in the video that the girls are some of the 223 school pupils still held by the group after it abducted a total of 276 on April 14 from the northeastern Nigerian town of Chibok. Some of the girls have since managed to escape.
In the video, Abubakar Shekau claimed the girls had converted to Islam, adding that they would not be released until all militant prisoners were freed.
Previously, he had threatened to sell the girls as slaves.
There has been no independent confirmation of the identity of the girls shown in the video.
International efforts to find the girls have increased over the past few days, with Israel being the latest country to join the search on Sunday.
Britain, the United States and France have already sent specialist teams and equipment to help Nigeria's military in its hunt for the girls, which is concentrated in the remote northeast of Nigeria where Boko Haram commonly carries out its operations. China and Spain have also offered their help, as international outrage at the mass abduction grows.
French President Francois Hollande on Sunday called for leaders to hold a summit in Paris to discuss security in West Africa, with a particular focus on Boko Haram.
Boko Haram, whose name translates loosely as "Western education is sin", has been waging a five-year insurrection in a bid to impose Islamic law on Nigeria, which has a half-Christian, half-Muslim population. More than 1,500 people have died in violence this year alone.
Nigeria's government has been criticized as being slow to respond to the crisis, and there have even been accusations that some government officials have colluded with the group.
Nigerian President Goodluck Jonathan has said he believes the girls are still in Nigeria. There are fears they may have been moved across the border into Chad and Cameroon.
DW (AFP, Reuters)