Where to find purchased items?

I am pulling my hair out, I paid to rent a film that was down loaded onto my computer but I cannot find it anywhere on the system the money's been taken but no film. Please could someone let me know where I am supposed to look for it?

I would also like to know why ringtones that are purchased through Itunes cannot be used on the iphone and only endup in the music folder on the computer and cannot be used on the iphone? this not the first time that this happended.