Join this lecture on quantum information and complexity where Richard Kueng explores the complexity of quantum circuits. Learn how almost all quantum circuits are exponentially expensive to realize in the quantum circuit model of computation, and discover how quantum complexity of random quantum circuits grows linearly with circuit size up to exponentially large circuits. The presentation employs versatile proof strategies from high-dimensional probability theory that have applications within quantum computing theory and beyond. This is the second in a three-lecture series that covers basic concepts of quantum information processing units (QPUs) and explores quantum complexity. Recorded during the thematic meeting "Complexity as a kaleidoscope" on April 3, 2025, at the Centre International de Rencontres Mathématiques in Marseille, France. The video includes helpful features like chapter markers, keywords, abstracts, and bibliographies to enhance your learning experience.