A 2008 "Saturday Night Live" skit featuring Tina Fey as Sarah Palin and Amy Poehler as Hillary Rodham Clinton is one example of how a viral video can infect a candidate with a poor public image. (Associated Press)

A 2008 "Saturday Night Live" skit featuring Tina Fey as Sarah Palin and Amy Poehler as Hillary Rodham Clinton is one example of how a viral video can infect a candidate with a poor public image. (Associated Press)