presidents pits stephen colbert against carole burnett and pete seger among others. >>> nelson mandela's death continues to be mourned throughout south africa and the rest of the world. the 95-year-old former south african president died thursday. because of his activism he spent decades imprisoned on robben island near cape town. we traveled there and spoke with an inmate about the harsh conditions. >> it took the 46-year-old mada mandela less than an hour by boat. he was not to make the return journey just to another prison for a further 18 years. these days it's a tourist destination. a brush with history and one with suffering. my guide was this man. >> you are viewing down there is between the wall. >> incarcerated here at 17 for blowing up a power plant. >> how many prisoners were there? >> 00. >> all political? >> all political. to such an extent they were trying to reduce our numbers. those two years, three years they want to take them to the mainland. from five to life they keep you here. >> you had do 18. >> i had to do 18. we tried at 6 to go to the mainland. >> did anyone esc