Mind & Psychology - 149 free documentaries about psychology.
Start with The secret to concentration - How to increase your attention span (43 min, DW Documentary), then Why People Are So Confident When They're Wrong (24 min, Veritasium). All 149 documentaries here are free to watch from their makers' official uploads. To read deeper, the top-rated book on psychology is Thinking, Fast and Slow by Daniel Kahneman.