This video is the next in a series about instructional design and technology integration.  It focuses on “weeding” (Mayer and Moreno, 2003 as cited by Mayer and Clark, 2010, p. 308).  Note the video in this post: https://ict-design.org/2013/11/28/instructional-design-and-technology-integration/ where cognitive overload occurs because of the split attention effect.  As a viewer, you are trying to focus either on the writing at the bottom of the screen or the verbal explanation.  The videos are nearly identical; however, in the video in this post most subtitles and music while speaking occurs was removed.  The effect is that it reduces extraneous processing by the viewer.

Reference

Mayer, R. E., & Clark, R. C. (2010). Instructional strategies for receptive learning environments. In K. H. Silber, & W. R. Foshay (Series Ed.), Handbook for improving performance in the workplace: Vol. 1. Instructional design and training delivery, (pp. 298-328). San Francisco, CA: Pfeiffer.