Some more details on the program: https://www.reddit.com/r/germany/comments/18rpwa/i_have_a_fe...
As an expat in Germany, I was very impressed by the whole system. You can scan your bottles, get a receipt and use that to subtract from your purchase in the supermarket (or get cash). If you have an empty beer crate full of empty bottles, the bottom of the pfand machine in the video above has a slot and a conveyor belt that scans the amount of bottles in the crate and adds it to your total (8c per glass bottle). If you order your groceries online, the delivery guy will collect your bottles and issue the discount on the spot. Homeless people often gather enormous amounts of bottles after events, such as Oktoberfest. People sometimes casually drinking on the street will leave glass bottles next to the bin so that the homeless guys have an easy time finding the pfand bottle to recycle.