I would be more inclined to purchase a DVD than subscribe to an online course. The reason being that my building time is affected by all sorts of variables: family commitments, work commitments, seasonal activities and variations....... If I had a DVD I could work my way through a build lesson by lesson at my own pace. If I had a subscription I would feel a need to keep up with somebody else's pace. This would lead to cockups caused by impatience, shortcuts etc etc etc.
Suggest that the DVD be accompanied by an ebook with plans of the instrument, useful jigs etc. You could even enlist Ken as a contributor.
I think that a DVD and ebook combination containing the accumulated wisdom of your knowledge and experience would be a tremendous legacy.
Miguel