Nice video, thanks for sharing.
I take a similar approach that has a fixed clamp that holds the blade for use on the Burr King. A well used 400 or 320 grit belt that at this stage approximates ~800 or 600 grit due to wear at a very low RPM. After the edge is set, a few passes on leather impregnated with white buffing compound.
I used to enjoy the challenge of stoning them freehand. I'd felt that this was a necessary part of learning to sharpen properly. Now and then I bring them out to see if I can still hold an angle but far and few between these days. Read that as way out of practice.