No - I haven't joined the Green Party, painted myself or Penny green, or been decorating. Since I got the MacBook and found out that iMovie could work with green screen photos or videos I've wanted to experiment. A few days ago I spotted an excellent 'how to' on the Instructables site and immediately stuck it on Pocket for future reference.
Today I gave it a whirl for the first time. First I took some video of the rain clouds which are plentiful here at the moment. Then I looked for a subject to add to that. In the end I chose a daisy and set up a Heath Robinson 'set' to take the photograph against a sheet of green paper:
The important thing was to try to evenly illuminate the green background so iMovie would have least difficulty in removing the colour.
Not perfect, and I think it might have been better if I masked out the daisy stem. The video wobbles a bit as I had the Lumix resting on a fence trying to hold it still against a blustery wind but the main thing was the idea worked:
For those with Macs and iMovie who want to experiment here is the link to the Instructable.