Think of the hundreds of thousands of dollars in sales were spent by those "ants" (i.e. customers) at that Wal-Mart on that day. Then, multiply by the number of stores in the chain x 24/7/365, and wallah!, you've got the retail Goliath that is Wal-Mart today.
Details on who made it and how it was done:
Read the Article at HuffingtonPost
Very impressive security-camera art! A must share!