One of my recent research projects has involved screencasting, the process of capturing computer screen video with audio narration.  I've specifically been observing 5th grade math teachers using it in a project-based learning environment.  They had their students produce tutorial videos explaining how they used different types of graphs to represent the distribution of colors in a skittles package.

First, students had to collect their data (i.e. count number of total skittles and respective colors of skittles in the package).  They then worked out all of the math: fractions, decimals, and percents of skittles in the package.  They then made graphs showing the distribution.  The students then began designing storyboard slides using SMART Notebook, a slide-based program not unlike PowerPoint that is made by the company that makes SMART Boards.  The students also wrote scripts for their presentations.

The screencasts were recorded using TechSmith's Jing (free program Mac/PC - www.jingproject.com).  You don't even need to record audio if you just wanted to do a silent video tutorial.

This project generally spanned 4-5 days, and their projects can be viewed on the school's internal website.

Here's a sample: http://www.screencast.com/t/NTllMzhl