On which DVDs? I don't recall performance footage of Kilby Snow at Newport, though he's watching the blues performers in Devil Got My Woman. The Ardoin footage was apparently out on VHS but not on DVD according to Suzy T. I don't recall seeing the diddly bow footage from the trailer either. But I might just not have prior incarnations.
The material from Newport on the other new DVD, Legendary Country Blues Guitarists, was mostly new to me. Son House, Skip James and Booker White playing together for instance. (Mostly Booker and Skip, with Son wandering around like a pain in the ass.)