I saw it but NO WAY can I believe that dog had that much water in his bladder. I suspect the person holding the leash must've been carrying a gallon container of water and a flexible tube led down the leash and under his sweater and then was aimed out to mimic peeing. For all we know it could even have been a female dog -- we never saw the actual penis with urine coming out of it.
But what I found quite remarkable is the balancing and walking on only his/her front legs. WOW!!