A rabbit attempts to play a church organ, while a knight fights a giant snail and a naked man blows a trumpet with his rear end. These bizarre images, painted with squirrel-hair brushes on vellum or parchment by monks, nuns and urban craftspeople, populate the margins of the most prized books from the Middle Ages. Michelle Brown explores the rich history and tradition of illuminated manuscripts. [Directed by WOW-HOW Studio, narrated by Adrian Dannatt, music by Jarrett Farkas].

You're lifting weights. The first time feels easy, but each lift takes more and more effort until you can't continue. Inside your arms, the muscles responsible for the lifting have become unable to contract. What's going on? Christian Moro explains how exactly our muscles operate, and what causes them to become fatigued. [Directed by Nichola Latzgo, narrated by Addison Anderson].

In 2012, a team of researchers set a world record, transmitting 1 petabit of data— that's 10,000 hours of high-def video— over a fifty-kilometer cable, in a second. This wasn't just any cable. It was a souped-up version of fiber optics, the hidden network that links our planet and makes the internet possible. What is fiber optics and how does it work? Sajan Saini explores the vital technology. [Directed by Artrake Studio, narrated by Addison Anderson].

Arcane books of forbidden lore, disturbing secrets in the family bloodline, and terrors so unspeakable the very thought of them might drive you mad. These have become standard elements in modern horror stories. But they were largely popularized by a single author: H.P. Lovecraft, whose name has become synonymous with the terror he inspired. Silvia Moreno-García dissects the "Lovecraftian" legacy. [Directed by Globizco Studios, narrated by Christina Greer, music by Manuel Borda]

Here's a shocking statistic: 50 to 80 percent of people in the criminal justice system in the US have had a traumatic brain injury. In the general public, that number is less than five percent. Neuropsychologist Kim Gorgens shares her research into the connection between brain trauma and the behaviors that keep people in the revolving door of criminal justice -- and some ways to make the system more effective and safer for everyone.

You've promised to get your son the cutest creature in creation: the cuddly. It's part of the Wuddly species, cousin to the terrifying duddly and the hideous fuddly. To make one, 100 eggs are placed in an incubator to undergo egg fusion, and the resulting combination will produce either a cuddly, a duddly or a fuddly. Can you make the right combination to get a cuddly? Dan Finkel shows how. [Directed by Artrake Studio, narrated by Addison Anderson].

Research shows that helping others makes us happier. But in her groundbreaking work on generosity and joy, social psychologist Elizabeth Dunn found that there's a catch: it matters how we help. Learn how we can make a greater impact -- and boost our own happiness along the way -- if we make one key shift in how we help others. "Let's stop thinking about giving as just this moral obligation and start thinking of it as a source of pleasure," Dunn says.

Hannah Gadsby's groundbreaking special "Nanette" broke comedy. In a talk about truth and purpose, she shares three ideas and three contradictions. Or not.

When you're feeling burned out as an activist, what's the best way to bounce back? TED Senior Fellow Yana Buhrer Tavanier explores the power of "playtivism" -- the incorporation of play and creativity into movements for social change. See how this versatile approach can spark new ideas, propel action and melt fear.

Why do we often neglect big problems, like the financial crisis and climate change, until it's too late? Policy strategist Michele Wucker urges us to replace the myth of the "black swan" -- that rare, unforeseeable, unavoidable catastrophe -- with the reality of the "gray rhino," the preventable danger that we choose to ignore. She shows why predictable crises catch us by surprise -- and lays out some signs that there may be a charging rhino in your life right now.