I came across this video last year and have waited for some time to see if something else would radically change my perspective in a greater way. Most of 2-10 on the list are posts here on LessWrong, so I thought I would share this as well.

The way that it changed my view is in reducing how much "benefit of the doubt" I give declarative statements about a person's intentions, and significantly increasing my perception of how commonly people collaboratively deceive themselves even when both parties are acting in earnest.