There is actually a membership cost to access their videos, but recently they made their accessibility tutorial videos available to everyone for free. The tutorial consists of 21 very easy to understand lessons. It starts with the fundamentals – some basic things to keep in mind while designing pages for people with not just low/no vision and hearing impairment, but also for those who have impaired mobility (e.g., make pages keyboard accessible). The videos are around 5 – 7 minutes long.
Video #6 is about screen readers. This lesson is a quick primer on screen readers and how they tend to navigate and read content on a web page. They show a quick demo of a free and open source screen reader called NVDA (Windows only), and put emphasis on a very important point – screen readers read content based on markup, not visual presentation.
The rest of the videos show how to include accessibility features in forms, tables, dynamic elements, and graphs and charts.
Here are all the accessibility videos.