These 19 seconds shows about a typical minute of work. The clip is running at 4X normal speed.
While everyone in this clip is actively working, I should mention that due to the heat the workers do take several breaks throughout the day, in addition to lunch. Their pace is still quite impressive considering the tropical setting.
If you multiply the effort in this tiny movie by over 100,000 minutes that crews of various sizes have been working on this project, then you’ll get some idea of the total work.