Kent, Ellis, and Peaty (2017) suggest that captions and transcripts of recorded lectures are of benefit beyond those with a disability they were originally intended for. While this paper was published in 2017, it is very relevant in the COVID-19 era, where lecturers are struggling to communicate to students online. Providing a transcript and captions on videos is an un-glamorous but effective way to improve learning, particularly for students who are not studying in their first language.
ps: I discovered this paper recently because it cites my blog (this blog): Worthington (2015).
Kent, M., Ellis, K., & Peaty, G. (2017). Captioned Recorded Lectures as a Mainstream Learning Tool. M/C Journal, 20(3), 1-1. URL https://journal.media-culture.org.au/index.php/mcjournal/article/view/1262
Worthington, Tom. “Are Australian Universities Required to Caption Lecture Videos?” Higher Education Whisperer 14 Feb. 2015. URL http://blog.highereducationwhisperer.com/2015/02/are-australian-universities-required-to.html