The previous lecture in this series is here. The next lecture in this series is here.
Prof. Zhao discusses a classic result of Chung, Graham, and Wilson, which shows that many definitions of quasirandom graphs are surprisingly equivalent. The expander mixing lemma is also discussed near the end of the lecture.
These videos are of a lecture course by Yufei Zhao at the Massachusetts Institute of Technology in 2019, and made available as part of its OpenCourseWare initiative. The website for the course may be found here.