The San Francisco State University hosts large number of course videos on various subjects including:
$\cdot$42 videos on Coxeter Groups
$\cdot$41 videos on Discrete Geometry
$\cdot$18 on Dynamical Systems
$\cdot$16 on Lie Algebras
$\cdot$43 on Matroid Theory
$\cdot$28 on Real Analysis I and II $\ldots$
All you need to do is click on the drop down menu "List all courses".