The Tehreek-e-Taliban Pakistan had claimed responsibility for the killings.
The 15 FC (Frontier Constabulary) personnel were kidnapped late last month after a night-time raid on a checkpoint in the northwestern town of Tank.
Pakistan's seven tribal districts near the Afghan border, including North Waziristan, are rife with home-grown insurgents and are strongholds of Taliban and Al Qaeda operatives.
The 2.38 minute video, a copy of which was obtained by AFP, was released on Sunday and shows the blindfolded soldiers sitting in three rows on a hillside.
The soldiers had their hands tied behind their backs and were flanked by two masked gunmen.
A middle-aged soldier, who identifies himself as Babar Khan, says in the video that he was captured with the others by Taliban militants who stormed their outpost late at night.
Then an unidentified Taliban commander wearing a leather jacket appears and says the group was taking revenge for the killing of 12 Taliban fighters in Khyber tribal district.
"We warn the government of Pakistan to stop killing our people whom they have arrested and if they continue to do so then Taliban will (kill) them like this," he says, before he starts shooting the captured soldiers with a Kalashnikov rifle, raising the slogan Allah-o-Akbar (God is great).
Other militants join him in shooting the captured soldiers.
FC commandant Majeed Khan Marwat told AFP that he had received the video and said that his men had been "martyred".
Officials said that the men were killed in Shawa, a small town in the North Waziristan tribal region near the Afghan border.