Marty.McFly said:

Has anyone got any idea if said footage exists? If so, link please! :)

In all seriousness, I'd love to see behind-the scenes images or footage of those recording sessions, as well. I haven't seen any before, though maybe with some of the new content in the eBook versions of the Making of Star Wars books, something will appear?

EDIT: The official Star Wars YouTube channel just posted this -- it doesn't include any footage of JEJ recording, but this old interview has Lucas talking about his and Anthony Daniels's performances.