I'd be interested in exactly how anyone uses one of these. I've watched the video and it only shows marking quite unrelated to making anything.
For example, I recently made some mortice and tenoned door frames. For the marking part of the job I had the stiles and rails clamped up in pairs, and used a try square across four or six pieces at once. Slide the try-square into position (with the ruler resting on it, on edge) then remove the ruler and mark the line all the way across. As far as I know this is normal practice.
When a mark is for a cut, it's done with a knife. To square round, the knife sits in the cut and you slide the square up to meet it.
For breadth and thickness, I use a marking gauge, not a ruler. I don't think poking the pin of the gauge through a hole in a ruler would be any easier.
And although the slots and holes on these rulers are undoubtedly spot on the numerical measurements, generally what matters is not a part's absolute size, but making it match something else - no numbers involved.
Am I missing something?
