There are many options available if you want to create and use screencasts in your classroom. I can see this being a beneficial teaching tool for older students especially. The teacher can instruct them on a new skill. Then later once the students have mastered the concept they can create their own screencasts to teach others. This would also be a good way for the teacher to test student mastery as well.
I made a screencast using Screencast-o-matic. I showed how to leave comments on a blog. I could not get it saved though onto my computer. (The link did work for me though when I tested it the first time.) It was very easy to create and I liked that I didn't have to download anything to use it. I told my husband I thought this would be a beneficial tool for him to use in presentations for his work as well.