If I buy the movie, can I keep it forever?

Yes, you can keep purchased films for as long as you want it, and watch it as many times as you like.

Films can also be re-downloaded from the store in some countries, but even if you are in such a country there is no guarantee that they will remain in the store for future re-downloading, so it's best to take your own backup copy of it.

Once you've downloaded it to your computer's iTunes, then you can find where it's stored by right-clicking (command-clicking on a Mac) it in the Movies part of your library and select 'show in explorer' ('show in finder') on a Mac and you can then copy it to a flash-drive, external drive, DVD etc (you can copy films to DVDs for backup purposes, but you won't be able to play them in DVD player).

By default your iTunes library is stored under :

• Mac OS X: /Users/username/Music
• Windows XP: \Documents and Settings\username\My Documents\My Music\
• Windows Vista: \Users\username\Music\iTunes
• Windows 7 and Windows 8: \Users\username\My Music\iTunes