Jonas,
I'm glad you liked the video. As for the shutter speeds, they vary from about 1/15 to 1/25, not nearly as wide a range as I had initially hoped. The speeds are adjusted by pulling out the short wooden dowel pin and changing the angle between both shutter petals, there being a series of holes that the wooden dowel pin can engage.
In actual practice, when I need a sub-1 second exposure time I use the shutter as-is, and modify the exposure with my choice of aperture plate, sorta like shooting in shutter speed priority mode.
I had initially thought about a spring-driven guillotine-style shutter (with the shutter blades travelling horizontally to negate the effects of gravity), but it ended up being too bulky and so I went with this rotating shutter idea.
~Joe