The video, which starts off with ISIS threat against the Tunisian state is believed to have been shot in north east Syria. The terrorists claim that the victim was a 'traitor'.
The terrorists have called the video 'A Message to the Monotheists After the Bombing of the Apostates in Tunisia'.
The original 11-minute video begins with a group of terrorists, some of whom have their bearded faces uncovered start listening to a pre-recorded rant in French on a lap top.
In the video a Kia Cerato drives slowly into shot. A masked prisoner wearing an orange jumpsuit is led from the vehicle by the driver.
One of the terrorists has been identified as a Tunisian national who is now operating from Syria.
ISIS has become increasingly active in Tunisia. Last month, at least 12 people died after an explosion ripped through a bus containing presidential guards in the capital Tunis in a suspected suicide attack.