Video: Four clips from 'Avatar'

More than ten years in the making, Titanic director James Cameron finally reveals the exotic alien world of Avatar to cinemagoers across the globe this week. The science fiction epic follows a disabled marine (Sam Worthington) who is able to walk again through a Na'vi surrogate on the moon of Pandora. He joins the blue-skinned aliens in a fight against humans attempting to harvest Pandora for a rare mineral.

Hit 'play' below to watch the four Avatar preview clips.