Environment or headphones in order to listen to the video
2 minutes to watch the video
A lifetime to think about the video after watching it
Step 1: Prepare your coachee's browser by going to http://www.dansimons.com/videos.html
Step 2: Click on the first video in the box and let your coachee watch
This video, and others that Professor Dan Simons provides on the above link, as well as a few more at http://www.theinvisiblegorilla.com/videos.html, highlight some very interesting things about how very real and/or very imaginary our world is to ourselves. And hence how complicated things get when interacting with others who are experiencing the same brain processes. This is a problem more of encoding than memory apparently as humans are much better at encoding "things" occurring near the core of our current focus than those on the periphery.
I first found references to this video in Karl Sabbagh's book The Hair of the Dog: And Other Scientific Surprises which contains a number of other really useful scientific surprises some of which I have incorporated into my toolkit.