Douglas Gordon : Through a looking glass.
I saw this last year at Tate Liverpool as part of an Alice in Wonderland exhibition. It takes a scene from the film Taxi Driver where Travis Bickle played by Robert De Niro asks "You talkin' to me?" whilst looking into a mirror and holding a gun .
"The two facing images, which begin in sync, progressively fall out of step, echoing the character's loss of control and his mental breakdown. These discordant projected images seem to respond to one another, thus trapping the viewer in the crossfire. In its almost dizzying play of dualities, through a looking glass perfectly articulates the dialectical inversions, doublings, and repetitions that are the central concerns of Gordon's work." (guggenheim)
There are two screens facing each other which play this scene, they start synchronised and then become out of sync so becomes a dialogue between the 2 screens which you are stuck between.