Say it together with MIKE: “eM… klaW… htiW… eriF”
There’s also a 3D version of the video, for those of you who have the Dr. Jacoby glasses:
Thanks to YouTube user psychologyguy for uploading these videos starring The One-Armed Man.
UPDATE: Here’s another recording of the moment, with a nice “twist.”
UPDATE #2: The actor did the same at the 2012 Twin Peaks Fest. Here’s that moment… BACKWARDS:
Al Strobel interviewed about the exact scene: