Pleasantville effect

You can create the pleasantville effect using the 'color corrector 3-way' filter to select 
the main color you want to select.

The first thing to find a clip that has an object with a particular color that you would like to change into (black and white) clip 

e.g. of Pleasantville effect:
https://www.youtube.com/watch?v=pPYjBHhUQZM