If you are shopping online for Christmas, you have to know that the books, CDs, all those electronic gadgets don't pack and ship themselves. Someone in the warehouse has to make sure the right stuff goes to the right place. And that is a tough line of work. So-called "fulfillment centers" are warehouses where workers are constantly monitored to make sure they are working as efficiently as possible at the same time as they are told to be flexible and make sure they're working safely. Gabriel Thompson worked at a San Bernardino electronics warehouse and tells us of his experience.