Democratic presidential candidate Hillary Clinton faced repeated questions about her use of a private computer server for emails while secretary of state during her recent Las Vegas news conference. Her discomfort with the topic was evident — especially if you compare her facial expressions in Las Vegas to her June 13 campaign launch announcement in New York. You can see the sharp contrast if you watch both events with the sound off, focusing on Clinton’s facial expressions and body language. Clinton is described, by both supporters and critics, as “brainy,” “tough” both personally and politically. In Las Vegas, however, her...