The article more or less says that some people could predict, with some success,next numbers in "chaotic" sequences, not "random". That might not be too surprising since chaotic in this sense has definite mathematical meaning. Even though chaotic sequences appear to have no recognizable pattern, they can be generated by mathematical equations (albeit non-linear ones). Therefore if someone could do this in their heads, they could "predict" the upcoming numbers. We've all read about people who have special abilities to recall trivia, calculate complex arithmetic sequences, calculate values of certain irrational numbers "on the fly", so maybe it's not that weird after all.