Help with loading movie on target

hi guys,
i have a movie clip that is the background of my site, a city…i have another one thats called rain (with some rain drops), i want the movie clip rain to play on my target movie clip (city) with a two minute interval…it rains then it stops, then two minutes after, it rains again and so forth (sorry for my english)

i would also be thasnkful for any help on how to load movies on the background…i mean…the site loads the user can navigate but the movie clip rain that will start only after two minutes loads wihtout the user seeing it load (like loading a section of the site while the user sees the main page, something like thisd)

thanks so much