Not sure if these have been brought to people's attention before but they're well worth checking out.

This first one is Sister Rosetta Tharpe doing 'Down by the Riverside' on a tv appearance. It doesn't come any better than this guitar playing gospel singer rocking out on a Gibson SG:

http://www.youtube.com/watch?v=dOmRm0-acJw&search=sister%20rosetta%20tharpe

(Bonus points to anyone who knows what film a clip of this was in)

Secondly, this is the only time Leadbelly was ever captured on film, playing three songs. The first song 'Pick a bale of cotton' shows how great he could play, and the last song of the three is an old chain gang song, immediately obvious from noise he makes inbetween every line. Essential viewing.

http://www.youtube.com/watch?v=Xj9YDCLOSUk&search=leadbelly

Enjoy!