Video explanation
A stone-laden sledge moves over sand; wetting the sand reduces the displayed pulling force and crew requirement. The focus is friction, not a complete reconstruction of pyramid construction.
Sand piles resist motion
Dry sand can pile up ahead of a sledge. Moving that pile requires force beyond a simple smooth-surface friction model.
Capillary bridges
A suitable amount of water forms capillary bridges, stiffening sand and reducing pile-up. More water is not always better.
History versus model
The effect offers a physical explanation for transport methods. Force, crew and moisture readouts are simplified model values, not archaeological measurements.