If you’ve ever wondered what audio description is, then the Microsoft video below is a good example. Audio descriptions tell people who are blind the visual information on the screen during natural breaks in dialogue. In the Microsoft example, the speech of the audio describer is a bit fast in places, but it shows the type of describing they do. The video was developed as a staff training video on disability awareness and the first three and a half minutes are dedicated to basic information. The video descriptions start at 3 mins 27 seconds into the video. They use different case studies to show where audio descriptions work well in enabling people to be productive in the workplace.
You can find out more about audio describing from Media Access Australia, and an article on a trial of audio describing with ABC iView.