sometimes they used a mechanical spring that then releases a valve to allow airflow. Slightly more indirect, but also an option. I think this one is probably mechanical actuation given the shape of the roller things, they seem to be like pulleys which would make sense for a little round nub going up/down when the hole passes by.
They're actually two entirely different peaces. UN Owen Was Her is a song written on a Midi system- computer with a piano program, it's utterly unplayable in it's full version.
The death waltz was written by an extremely sarcastic asshole decades ago.
Yes, there is no connections between both, one being from an 'artist' decades ago as you say (its quite funny tho, especially for a musician) and the other being from touhou. It's sounds quite nice on a piano, I'm actually trying to learn it.