One of the cavers happened to find a hidden chimney near the ceiling of the cave, barely large enough for his body to fit into. The chimney dropped forty feet to a small chamber full of what appeared to be human bones.
The access to the chamber was so small that the paleoanthropologist and his usual team could not enter the sight.
This Nova production runs just under two hours, but is fascinating. The video begins with a first dig near Johannesburg that introduces an earlier find, but after about one hour it focuses on the Naledi cave find.