Modern ejumacation has gone multimedia and Powerpoint, often multimedia within Powerpoint. Some like 3Blue1Brown are brilliant at it (the multimedia, not Powepoint), others less so. Here’s a random assortment of lectures where good old chalk and boards prevail: E&M from IIT Madras, chemistry and cryptography from Ruhr Universität, Bochum, Fields Medalist Cédric Villani on something-or-the-other, and an early calm-for-him presentation by Jens Fehlau on the Leibniz integration rule made famous by Feynman. Finally, a tribute to a popular chalk, recently discontinued.
Youtube Channel: nptelhrd
Youtube channel: ChemieRub
Youtube channel: Introduction to Cryptography by Christof Paar
Youtube channel: Institut des Hautes Études Scientifiques (IHÉS)
Youtube channel: Flammable Maths
Youtube channel: Great Big Story