Minneapolis director/actor Craig Johnson presents an illustrated talk about his experiences and study of directing in the theater. Lots of pictures, a few stories, and some history. Pro-tip: watch at 1.5 speed -- I sound much smarter and you'll cruise through the material more quickly. You'll find that under settings and playback speed.
For further study, three readable directing books with different, but useful perspectives: Tips: Ideas for Directors (Jon Jory); Notes on Directing (Hauser & Reich); The Director's Craft (Katie Mitchell).