For someone like me who is interested in phonetics, phonology that shit, this is highly interesting!
http://www.media.uio.no/personer/arntm/McGurk_large.mov
Watch the video once through. What is he saying?
Then watch it again but close you eyes and only listen. That is what he is actually saying.
What we SEE is effecting the way our brain interprets the sound.
Try opening and closing your eyes in time with each sound.
Basically the audio of one sound has been synce with the video of another sound.