The footage shows Hay’at Tahrir al-Sham HQ located in a desert area of Idlib province.
The facility is a tunnel with nine separate rooms. It is supplied with electricity, water and sanitation. However, judging by the the lack of furniture and special equipment on the footage, the HQ wasn’t operational at the time.
Apparently, the HQ is located in a desert area and buried underground to hide it from the imagery intelligence of the Syrian Armed Forces and the Russian Air Force. The exact location of the HQ remains unknown.