I reviewed the Instant Video Presenter software and despite some negatives, I would recommend getting it for anyone who wants to create video presentations using a green screen.  For DE I like the idea of increasing teacher presence by allowing students to see and hear the prof or tutor.  Here is my summary:

Positives(http://www.instantvideopresenter.com/t-features.aspx):

• Easy to use and comprehensive tutorials walk a person through setup to the recording process(http://www.instantvideopresenter.com/t-trainingvideos.aspx);
• Easy to adjust a video camera to the green screen.  Program includes a wizard feature that is very convenient;
• Does not require an investment in a lot of expensive, video gear;
• The web site has picture galleries and high quality PowerPoint templates for download that are adjusted for including a person on the screen in the left or right positions (http://www.instantvideopresenter.com/t-templates.aspx);
• System requirements for the software are reasonable (http://www.instantvideopresenter.com/t-requirements.aspx);
  

Negatives:

• Although it does not require an expensive video camera, it does not work well with the built-in web cams in laptops.  I recorded a couple videos but it was of poor quality.  The green screen did not always work with the laptop's web cam;
• The software did crash a couple times when I was recording but I'm not sure if this was due to the laptop webcam;
• Lighting is a concern and there are a few tricks to setting up a properly lit area to record quality video (There are some excellent lighting tips are given in a video tutorial);
• You need some type of hand-held device to operate a PowerPoint slide show or to switch the screens while recording the video (like a weatherman has when doing the weather report);
• Need to be close to computer to record using sound. You need a clip-on mic to record sound if standing far away from the computer. Otherwise a mic hanging overhead (boom mic) off-screen will have to be used.

This is the simplest program I have ever seen for recording and producing a high quality video.