Chroma key technique

A technique I would like to use for my video to create the effect of having a fridge within a fridge within a fridge in order to encode meaning to the audience that the subject is on drugs is chroma key.
I am doing this blog post in order for me to understand and remember how to do this technique when I come to editing.
I was given a tutorial in class on how to do this and created a video with some footage I wasn't using for my video but filmed previously and also footage of someone opening a door with the green screen behind it. Here is the video:


greenscreentestnsound from emily smith on Vimeo.
Here are the steps on how to remind me how to use the chroma key technique.

• I need at least two video lines. The shot with the green screen needs to be on the top line and the footage going in the green screen needs to be underneath the way to remember it is that its like a sheet of glass and something underneath it.
• Then select the top clip and add the chroma key effect by going to 'Effects'- 'Video Filter' - 'Key'- 'Chroma Keyer'
• Under the Chroma Keyer tab I can adjust the colour to match the same as my green screen.
• The green area of the clip should become clear and you will see the video clip on the layer underneath.
• I may then need to move the clip underneath to fit in the transparent area.