Jing is a program which allows you to capture images and videos of what you see on your screen. Imagine you are trying to demonstrate how to execute a technique in Word or PowerPoint. You could sit another person beside you and let them watch your screen as you explain what you are doing. That would not work, however, if the person was 1,000 miles away. With Jing, distabce does not matter.
Jing allows you to record videos of what you are seeing on your screen along with your commentary. There are two versions of Jung, with one of the them being free. The free version does limit you to 5 minutes of recording time for any one video.
As a next step, watch the video that is located on their homepage. It provides a thorough explanation. The website is http://www.jingproject.com