For my final assignment, I had my students dance across the front of my green screen.  The screen is very small so I had to edit out a lot of the edge shots.  The lighting I have is not great, so some of the scenes still have a bit of spill from the green screen.  I used the keyer and changed various settings in After Effects but couldn't get all of the spill out of my video.
Once I keyed out the green screen, I added a background, created stars in Adobe Illustrator, animated the stars in After Effects, then added background music.  (A recording of the 8th grade choir singing Don't Stop Believing).  At first my audio would not work, then my file was too large to upload to the Adobe Exchange.  Then.... I forgot that I changed my YouTube password and had to jump through a few hoops to get it straightened out. assignment was uploaded (I hope) and is posted below.
I'm looking forward to working with After Effects in the future and learning about more of the possibilities available with the software.
Here are a couple of other class video projects where I used the green screen: