At the Calgary Comic & Entertainment Expo (April 28, 2012). When asked what their favourite villain in the series was, Patrick Stewart started to indicate his favour for the Ferengi & Daimon Bok until John de Lancie showed up... (Props to the guy in the crowd that shouted out "Wil Wheaton", though!)
Video is out of focus initially, but improves after a few (15ish) seconds...
