High water bill explained

Jennifer and Jim kept getting huge water bills. They knew beyond a doubt that the  bills weren't representative of their actual usage, and no matter how  hard they tried to conserve, the high bills continued, with some  being larger than others. Since they could find nothing wrong  themselves, they had a plumber come out and check everything for leaks  or problems, including the water meter, outdoor pipes, indoor pipes,  underground pipes, faucets, toilets, washer, ice maker......EVERYTHING  to which their water line was connected -- all  to no  avail.
One day Jim was sick and stayed at home in bed. Not long  after his wife left for work, he was awoken by hearing running water.  He finally figured that it seemed like something downstairs running. So  he finally conjured up enough strength to get himself out of bed to  investigate, and it was then he stumbled onto the cause of their really  high water bills. Apparently this was happening all day long when they  were not at home.
He called his wife home, and then  knowing that few people would ever believe them, he and his wife video  taped a segment of the 'problem' for all posterity so as to have a film  of this unbelievable 'leak' -- see attached  video.