This is what most cruise passengers will never get to see. Mein Schiff 3 is under construction for TUI Cruises at the STX Finland yard in Turku, and the crew is testing the evacuation systems they would use in case they would be ordered to abandon ship.
Yes, the video is in German, and no, there is no English translation available. It's not necessary to speak German to figure out what's going on, but if you do, you'll have an even better understanding.
Video courtesy of TUI Cruises