I do a lot of instructional video, and I started scripting my videos a long time ago. It makes a world of difference in the final product. If the questioner has Camtasia on Mac, hare's what I'd suggest. Get a free teleprompter program from the Internet. Then, record yourself on your webcam delivering your script. With a little bit of practice, you can do it without the audience being able to tell you're reading from the screen in iMovie. Then, play it back in iMovie, while you record the corresponding screencast video clips in Camtasia. Finally, edit the final in Camtasia, laying the screencast clips over your webcam video at the appropriate places. It will elevate your videos from a very amateur level to a fairly professional one.
