I was finally able to view your video. Technical problem on my end. I thought your video was very interesting because it made a point that I made in another post in response to Bulldog (Jim). Read that post here…
It’s always been my understanding that grayscale was used for depth, not for tone graduation. And your video sort of proves that. If I look at the test pattern in your video that’s shown starting at 1:56, you’re making the point that you don’t really see any tonal difference in any of the squares. You’re right, you don’t. But what you DO see is a very marked difference in the depth of the engraving of each square. In other words your laser is already burning the material as dark as it’s going to get with the laser/material combo. The grayscale is simply determining how deep it’s going to engrave by varying the power.
Make sense?
Run that same test using a dither such as jarvis or stucki and I think you’ll see a definite tonal difference in each square.