If you are taking mathematics courses related to combinatorics or probability, I found a page from UCLA containing hundreds of video lectures on the said subjects. It is a collection of lectures from 1993 up to the present and includes lectures from famous mathematicians such as Terence Tao.
In addition to the 5000 videos that I have shared to you last year, I have recently discovered more than 1500 links to mathematics video lectures in Pinterest. The links cover a wide variety of topics which include K-12 Mathematics, Math Interviews and Humor, Famous Mathematicians, Student Lectures, and many more.
The collection also includes undergraduate and graduate content topics such as Abstract Algebra, Graph Theory, Topology, Number Theory, Optimization, etc.