FYI, I just uploaded a video demonstrating how you can use Etoys to create a Green Screen effect.

To do this I purchased a $30US Green Screen, but it can also be done with a green folder (~$0.35US).  Kids can use this to create their own stop motion animations, recording a set of movements once, then re-using that set of movements in multiple scenes, with different backgrounds and other "actors".

In the next Etoys Minute and hopefully Blog Post I'll do a Squeak code walk through of code and post a link to the project so others can try it for themselves.

Stephen