a coworker is moving towards free thought

One of my co-workers mentioned some video he's watching and seems to be excited to be moving towards free thought. I was going to suggest some channels to watch on YouTube starting with qualiasoup and Theramintrees to help him learn and absorb critical thought.

Has anybody else got some good videos to watch on critical thinking and free thought? He is not particularly religious, but it seems open to learning not particularly atheist things, but starting with more open-minded videos.