Please go under the "Options" tab and fill in your Google API Key in the field "Google API Key."
Check out the help link next to that field for detailed instructions on how to get the API key (takes less than 1 minute).
Do keep in mind that for some Amazon products there may not be any YouTube videos available. You can go to YouTube and search for the product's name, to see if this is the case.
Article ID: 143
Category: Associate Goliath Wordpress Plugin