Window media encoder is a free program from Microsoft. It has a number of uses, including the conversion of mp3 audio files into more compact .wma files using the convert a file function and capturing video files produced via a webcam so that they can be played over the internet (capture audio or video). My favorite use is the screen capture tool that enables you to record video with audio commentary showing events as they occur on your computer screen, either in a specific window, part of the screen or the whole screen. By opening a student paper in Word, for example, you can provide an audio commentary of the student's work, moving the mouse pointer to highlight the part of the work under discussion.. You can provide step by step instructions on how to use a software function such as the equation editor, or you can give a guided tour of your webtycho classroom, to name just two other other possible uses
Windows media encoder can be downloaded here.