Brilliant Physics puzzle films Advent calendar: Physik im Advent

Who needs a chocolate Advent calendar when you can have http://www.physik-im-advent.de/ You can decide whether to have it in German (DE) or English (EN) using the toggle switch in the top left hand corner. The film of the answer comes up the next day. If you look at days that have already gone, the answer film comes first but scroll down for the original problem.