STORY: One of the men shown, alleged to be a commander, said his separatist forces were trying to ensnare Ukrainian troops in the region.
"We will continue to make inroads into their lines to encircle them fully and, I think, if they're not idiots, they will surrender," one unnamed military person was shown saying in the footage.
"If they don't want to surrender... they will die," he added.
The footage was also said to show weapons and personal effects left behind by retreating Ukrainian forces, as well as corpses left under a destroyed road bridge.
Reuters was not able to independently verify the contents of the footage released by the separatist police force.
Hirske is a small town to the south of Sievierodonetsk and Lysychansk, two cities where an intense battle between the pro-Russian and Ukrainian forces has been reported for weeks.
Moscow says it is engaged in a "special military operation" to disarm and "denazify" its neighbour.
Ukraine and its allies accuse Moscow of unprovoked aggression that has killed thousands of civilians and flattening cities.