Skellig is the Irish monastery of Skellig Michael on island in the North Atlantic. Known for being one of the best preserved Irish monasteries but also one of the hardest to reach. It was built in 588 and not abandoned until the 12th century. You see it at one point in the video where there are a few buildings clinging to the side of an incredibly steep mountain face. The stone beehive cells you see in the video are either on Skellig Michael or of the type that were there.