The video slit-scan effect (used in 2001 A Space Odyssey, classic Doctor Who, Star Wars, etc) is created by filming a moving pattern behind a fixed slit and moving the camera towards the pattern and slit, and repeating this process for subsequent frames. With each frame having the camera start moving from a position slightly further back. The film is not allowed to roll, so each frame is exposed to the outline of the slit as the camera moves closer.

Since I couldn't find a demonstration on how to do this type of tunnel effect in After Effects (aside from the two infinite planes variant); I built my own emulator in flash.

[UPDATE]
Source .fla CS3 file >[link]
Anyone who wishes to use this is welcome. If you do, please send a link back so I can see.