I learned about "Buck" after watching and enjoying Robert Redford's "The Horse Whisperer." This movie is a documentary about Buck Brannaman, the real-life "horse whisperer" who served as a consultant to Redford.
Dan M. "Buck" Brannaman (born January 29, 1962) is an American horse trainer and a leading clinician with a philosophy of handling horses based on classical concepts from the vaquero tradition; working with the horse's nature, using an understanding of how horses think and communicate to train the horse to accept humans and work confidently and responsively with them. One of Brannaman's stated goals is to make the animal feel safe and secure around humans so that the horse and rider can achieve a true union.
If you love horses (or animals in general), you will appreciate this movie. I don't know if it's available for streaming; I found the DVD at our local library.