Taryn Eason has Ehlers-Danlos Syndrome, a condition that gives people overly flexible joints and stretchy, fragile skin. It also allows for some really great party tricks, as Taryn demonstrates with her hands. Her fingers can do a ridiculous amount of stretching, which she reveals with a smile on her face for the entire video. She's probably happy to do it because it made her famously popular in elementary school. It's a remarkable use of her hands, right up there with the guy that can pull moles out of the ground and this deaf man's mesmerizing finger dancing.
It's great that Taryn has decided to embrace her quirky talent. It more than makes up for never being able to accept the declaration of a thumb war. Also, it's unclear whether or not she has an extreme advantage or disadvantage while solving a Rubik's Cube.