Take a quick look at this lesson – which has two screens, a video of the lecturer on the left – and the words he is speaking, on the right. This provides a double whammy, that makes the total experience more effective.
This not hard to do – and a simplified version, using only audio and video can be used. Where the instructor is speaking in the background – while the actions he is performing on his computer, is shown in a video in the foreground. Only one window is used.
The basic idea is simple – different technologies can be used simultaneously to provide different approaches to the subject.
To give a better learning experience.