At around 1 min 35 in the video, they show the plumbing inside, and for some reason theres an s-bend in the pipes. What the hell for? Think about it- it doesn't have fresh water flowing into the top part. Its all piss, therefore there would be a volume of stinky, hot piss trapped in the s-bend at any given time, and when the truck came along and tipped the bin up to empty it, that trapped volume of piddle would run out and all down the side of the bin (and probably splash the inside of the trash cavity of the truck, too).
The four-eyed galoot who thought this one up should stick to making chocolate and being neutral in wars. Oh, and keeping all those secret bank accounts safe.