Found this in the extras of a DVD on Septeto Nacional. Listed as Carlos Embale y Coro Folklórico, I think that's Amado Dedeu on claves, later of Clave y Guaguancó and also featured on the Rapsodia Rumbera albums.
No date on this, but interesting how they incorporate the batá in the montuno.
This tune was composed by Ignacio Piñeiro and is usually known as "El Desengaño de Los Roncos." (Los Roncos was the name of a "Coro de Clave" directed by Piñeiro.
Download the mp4 of this clip from rapidshare. (23MB)