I think a lot of the B&W footage from the 70s originates from the Bill Graham archives, I believe he filmed every show he produced in B&W with no intent of it ever being commercially released. The stuff Voodoonala uploads replaces the mono camera sound feed with soundboard recordings that are in circulation, he does good work and the videos are fun to watch.
Looks like this weeks Friday Shakedown Stream is going to be the "Closing of Winterland". I have this on DVD and it is really good. Hoping future weeks will bring more previously unreleased material but it doesn't surprise me that, so far, this is mainly being used to promote existing product.