I'm sorry, but I can't see the video in the USA. However, I think I know what you want to do. You want the green-screened people to become invisible. In their shapes, you want to put new video.
This is easy. Add the video that you want to fill the people-shped hole to your comp. On the layer above, add the green-screen people. Now go to the lower layer, and use the green-screen people layer as an Alpha Inverted Matte. You will see your replacement video in a people-shaped hole.
only a question. how can i layer as alpha inverted matte. on a video i saw that near the file there is a menu called mode. but i haven't this menu. i have after effects cc 2014. i know that is a stupid question but i don't find this option.
i have just founded the menù. perfect. thank you very much. there aren't italian tutorial about this problem.