Markus sez, "I was participating the WSIS in Tunis. One evening there was a event, organized by the Brasilian ministry of culture. Gilberto Gil gave a prize to Richard Stallman for his work on freedoms. Later on that evening, both did a jam-session together. Richard sung and Gilberto played the guitar. I did some short videos and they are now online."
(Thanks, Markus!)