I heard you saw the movie ‘Avatar’. I haven’t seen that flick

The word flick is being used as ‘slang’. A word used as ‘slang’ is not used in a manner typical of its meaning.  Flick is another name for ‘movie’, ‘film’, or ‘motion picture’.

[聽說你看過阿凡達啦，我還沒去看呢！]

本句中的flick是比較口語的用法，與電影movie的用法相同。