True, and it states that clearly in the opening scene. There is plenty of relevant info in the video for people that want to build one, and they can take a course or find plans for the details.

The cruck timber frame is a scribed structure, and we have a video of the course we do every year at www.heartwoodschool.com/cruck.html. Our 2018 course just ended, but we will offer it again next year. Please fill out the interest form on our website to get updates.

That is a cruck timber frame, and we have a week-long course that teaches the scribing and other techniques to build one. Please visit our website for our schedule, and there's a short video included on the course page.

Cruck Framing course at Heartwood May 4-8, 2020. Registration opens Dec. 1. www.heartwoodschool.com

Not from us, sorry. I'm sure a web search would turn some up.

Lowering the diameter of the spindle would help, but not by much. You'd need any type of torque converter like a pulley or gearbox for a significant change in rpm.

I was referring to revolutions per stroke, not speed of the shaft. I might try a much longer spring-whip, and a longer treadle(which would operate the spring in a significantly longer distance of travel).

Whether you're referring to rpm or revolutions per stroke, my answer still applies. A longer spring-whip and treadle will only get you so far and will make it awkward or even dangerous in extreme cases to operate. The best thing to do is decrease the diameter of the spindle to increase your revolutions per stroke, otherwise you'd need a torque converter.