Step 1: Step 1
Again, this method only applies to PCs.
The first thing you are going to need to do is open up Notepad (if you don't know what that is, search for it in the start menu. It's for coding things, or otherwise known as magically making things happen with weird letters). Don't worry, it's nothing complicated. Like, at all. Honest.
Notepad will need to be run as the administrator for this step to function correctly.
If you're not the administrator of the computer, right click Notepad and choose "run as administrator". Click "Ok" if prompted.
If this fails, ask whoever's the administrator of your household to go on their account and let you do this.
If that fails too, forget the whole thing. Sorry. :P
Anyhow, copy and paste the following into notepad, and leave it open for now:
<Transition name="Bluescreen" iconid="12" comment="Makes first clip show through blue areas of second clip">
<Param name="KeyType" value="1" />
<Param name="Similarity" value="100" />
<Param name="Progress" value="0.0" />
Step 2: Step 2
Name the file "Bluescreen.XML" and save it in this location:
Program Files > Movie Maker > Shared > AddOnTFX
If you don't see a folder named AddOnTFX, make a new folder with that name inside the Shared folder.
Step 3: Step 3
If you do not own Windows Movie Maker 2.6, which is typically true if you use Vista or Windows 7, you're going to need to download it. Don't worry, it won't replace the fancier version that your system came with. Here's a link for download (it shouldn't be a long process as it is a fairly old program):
If you own it, obviously you're free to go on to the next step.
Step 4: Step 4
Take a video or even a picture of your preffered subject in front of a blue blanket, tarp, or whatever-the-heck-else-that's-flat, typically something as close as you can get to the shade shown in the picture; ie, a video you walking in front of a blue tarp. (Yes, I know I said greenscreen, but the color you'll need is blue!) Quality of the video you're making depends mainly on the shade + flatness of the screen and the complexity of shapes in front of it.
Now get a video or picture of whatever you intend the background to be - ie, a picture featuring a magical landscape of unicorns and butterflies.
In the sample, the ghostie will be exploring the world of trippy colors.
Open up Movie Maker 2.6 and import the subject and background you just got. (File > Import into Collections)
Drag both media into the timeline and cascade them onto each other by dragging.
Once this is done, open the Transitions tab and drag Bluescreen underneath the duration of these two clips.
If it doesn't work, reverse the order of the clips.
PRESTO. Cheap effects have been made!