Ah damn you should put up spoiler alert now I know what those buttons in video 2 do already ):
:(
(Spoiler) The manual also tells you why the coin door takes 20 wires on page 51.
EDIT: I pulled out my coin acceptor to compare. It's got 3 wires: ground, +12V, and coin (pulses hi for 40ms when a coin passes through). Interestingly enough you program it by putting in 30 coins of the same thickness. That's cool because 1) I can program it to work with any country's currency and 2) I can program it to only accept flattened bottle caps. The one in Badspot's machine is way cooler (and also not a cheap piece of plastic stuff like mine) although it probably only accepts quarters and quarter sized tokens.
A beer bottle cap powered arcade machine would probably be a hit at parties though. Could stick an
alcohol sensor in it that doesn't let you play if you've had too much to drink.