I'm planning to use the think-aloud protocol for an upcoming usability test. A book chapter on think-aloud suggested that you show the participant an example video of someone thinking aloud. I think this is a good idea to reassure users that they are 'doing it' correctly as to get the best information from them.
That said, do any of you know of a good video to use for this? I'm thinking of using a video from a past test, but wanted to avoid that if possible.