Nests of red harvester ant, Pogonomyrmex species, usually have one central opening in the middle of a circular area cleared of vegetation by the ants. The area is characterized with small pebbles excavated by the ants while digging their subterranean galleries where the colony lives (Texas AgriLife Extension Publication E-402 Red Harvester Ants).
During her graduate studies at Texas A&M University, Nancy Nicholi was taking this video when a dime dropped from her pocket onto the ground near the nest opening. She was able to capture the response of the worker ants as they worked together to move the dime away from the clearing around that opening. Movement of the dime on the surface is reminiscent of a planchette or movable indicator point on a ouija board (correctly pronounced "wee-jah" although often pronounced "wee-gee")! It is a great example of discovery and may constitute one example of a stupid ant trick.