Yes! Educational research supports being casual and conversational. Although for drawing diagrams, a physical overhead with the instructor's hand visible seems to work far better than Khan style video.
See: Fiorella, L., & Mayer, R. E. (2016). Effects of observing the instructor draw diagrams on learning from multimedia messages. Journal of Educational Psychology, 108(4), 528.
See: Fiorella, L., & Mayer, R. E. (2016). Effects of observing the instructor draw diagrams on learning from multimedia messages. Journal of Educational Psychology, 108(4), 528.
https://sci-hub.se/https://doi.org/10.1037/edu0000065