PowerPoint MVP Austin Myers has developed a step-by-step tutorial on inserting closed captioned video in PowerPoint.
Austin adds, As we build presentations with video, we often overlook the fact that many people suffer from a hearing loss and cannot hear the audio portion of the video. In the past, it wasn’t feasible to add closed captioning to video in PowerPoint because you could not place text “on top” of a running video from within PowerPoint. We recently found a method to change this and allow users to both create a closed-captioned video in PowerPoint and distribute it to others.

