Delighted to see on that video that the Sergeant-Major pictured really was a Company Sergeant-Major wearing the correct rank insignia of crown on forearm. The crown above three stripes, which actually represents a colour-sergeant of staff-sergeant, is often mistaken for a sergeant-major's insignia, probably due to confusion in that three stripes indicate a sergeant and a crown on the shoulder a major. But this is a terrible solecism, which got that famous 1981 tv adaptation of "Bridesheaed Revisited" off to a dire start.

~Michael~