However, there is an interesting discussion here about this difference in stamping.
Beginners: lift the shinai up and then moving forward as you cutAnd I think this makes a lot of sense. Perhaps Grumpy just starts off with the intermediate stage?
Intermediate: lift the shinai up as you're moving forward with your right foot
Advanced: move forward with your right foot and then lift your shinai up and cut
This improve coordination and timing, as you have to improve your arms' speed to achieve the third stage
My big men cut has gotten faster so that now my body cannot keep up, and I've started trying out the second way of doing it. My ki-ken-tai-ichi is really good, but I have found that I tend to bend my body a little when I cut, perhaps because of lack of body strength. I have to work on that now.