Steven Pinker talking about how language helps scientists understand cognition.
Steven Pinker: Linguistics as a Window to Understand the Brain

Nicholas Christakis talks about important revolutions in understanding the social sciences.
Nicholas Christakis: The Sociological Science Behind Social Networks and Social Influence

Benoit Mandelbrot interview, talking about fractals.
Big Think Interview with Benoit Mandelbrot

Richard Dawkins interview, talking about evolution and other related topics.
Richard Dawkins – Evolutionary Biologist – Big Think – discussing a multitude of scientific topics

First time I have heard about Stewart Brand; really smart and wise guy.
Big Think Interview With Stewart Brand