IS released the video on Tuesday showing two local men being executed in separate incidents, one by decapitation and the other by drowning, for allegedly spying for the Iraqi military.
The first victim identifies himself as Mahmoud Mostafa al-Tai and admits to informing the army of IS positions in the flashpoint city before a hooded executioner beheads him on the roof of a building.
The second victim says he provided information on the location of IS commanders homes, which were later bombed by "US warplanes".
The extremists then play audio recordings of the victim communicating with Iraqi officials before he is drowned in a large tank of water by a masked militant.
Defectors and informants have reportedly been regularly executed in Mosul since an offensive was launched on October 17 to retake the city.
|The video shows multiple suicide car bomb attacks [Twitter]|
The 42-minute video titled "the procession of light" also shows multiple suicide car bomb attacks against clusters of Iraqi military vehicles in Mosul, including attacks carried out by handicapped and teenage militants.
IS have used numerous suicide car bombs, booby traps and mines as they battle to defend what remains of their territory.
After a lull in the assault on Mosul, Iraqi forces started a fresh push last week, engaging in heavy fighting in eastern Mosul.
Iraqi forces now control more than 60 percent of Mosul's eastern half.
Last month, IS released a video purporting to show two captured Turkish soldiers being burned alive in northern Syria.
The video showed two uniformed men being hauled from a cage before being bound and torched, sparking outrage in Turkey.