From the Classic Blues Videos website:

Sonny Boy Williamson II performs “Nine Below Zero” at the American Folk Blues Music Festival in 1963. Introduced by Memphis Slim, with Otis Spann (piano), Matt Murphy (guitar), Willie Dixon (bass) and Billy Stepney (drums).

Thanks to Classic Blues Videos for hipping me to this clip.

— A Days of the Crazy-Wild blog post: sounds, visuals and/or news –-