A rousing slippering of the drum by the BD in this video

https://youtu.be/k4gBykQylm4

Any ideas what ( if) different drum head material or dampening would give this somewhat old style flat sound facilitated by hard mallets. Reminiscent of a fife and drum band sound....maybe it’s that simple an answer though,to me, quite a departure by the RHRBW for a pipe band. Sounds ‘good’ though as a change up.
Sort of unorthodox beating protocol employed too....wondered if HRH had to authorize that via Inchdrewer House.