I remember reading somewhere that those shuttles were in an old hangar that collapsed on top of them. Looks like that wasn't true, this was definitely shot fairly recently, drones and all.
At one point in the video they mention that this is what happened to the only Buran that actually was in space. The ones in the video were never completed/in service it seems.
They actually mention the hanger collapse during the video, that was the only ex-operational Buran that got crushed. The hanger in the video is the one that houses partially completed Burans.