The footage was shot before the attacks in November 2015 but was published yesterday.
It is not clear when exactly the footage was filmed.
Among those who carry out the beheadings is Bilal Hadfi, who was killed during the Paris attacks. "You destroy our homes and kill our fathers, our brothers, our sisters, our mothers and our children," he says into the camera.
The video shows pictures of Tower Bridge and St Paul's Cathedral in London, and claims Isis is ready to strike "any time, anywhere".
A few minutes later the face of John Bercow, the Speaker of the British House of Commons, appears on the screen with a crosshair over his face.
Then the footage ends with the message, "Whoever stands in the ranks of kuffar will be a target for our swords and will fall in humiliation," superimposed over an image of Prime Minister David Cameron.
The film is more brutal than previous propaganda videos as it does not cut away before the victims are beheaded.