That's genious! Allthough it doesn't make sense that it's reversed. Why would he throw away that many beers and as "Nice story bra" makes a point with; "Why whould they creat a machine that drains beer out of cups?" And then put the 'used' cups back in the row....
It is a suction tab that gets pushed up and seals after beer is in it.
plus, why would they create a machine that drains beer out of cups? think bro
http://www.wired.com/gadgetlab/2010/12/how-it-works-beer-dispenser-fills-glass-from-bottom/ There you go.
Watch it in reverse and maybe you'll figure out how they did it :P http://playgif.com/8889#reverse
use the knowledge of that brain the universe gave you, the woman in the back is brushing her hand through her hair, this time look at it in reverse, her actions are weird and so are his.