Click through to YouTube for the explanation in the notes - they don't work through the night:
"to explain the video in detail: 48 hours of construction time is the accrued time of construction. workers rest after 10pm everyday. As you may see on the left corner the clicker registers 46 hours as time to finish the main structural components, and another 90 hours to finish the building enclosure. For a building of this size a conventional approach would take anywhere from 3 months to anything goes."