Facebook ex-security chief Alex Stamos outlines potential threats to the 2018 and 2020 elections, as well as possible solutions to safeguard future elections. Subscribe on YouTube: bit.ly/1BycsJW His interview is part of an upcoming two-night FRONTLINE documentary, "The Facebook Dilemma." Watch "The Facebook Dilemma" starting October 29: www.pbs.org/wgbh/frontline/film/facebook-dilemma/ Twitter: twitter.com/frontlinepbs Facebook: www.facebook.com/frontline Google+: plus.google.com/+frontline/posts FRONTLINE is streaming more than 200 documentaries online, for free, here: to.pbs.org/hxRvQP Funding for FRONTLINE is provided through the support of PBS viewers and by the Corporation for Public Broadcasting. Major funding for FRONTLINE is provided by the John D. and Catherine T. MacArthur Foundation and the Ford Foundation. Additional funding is provided by the Abrams Foundation, the Park Foundation, The John and Helen Glessner Family Trust, and the FRONTLINE Journalism Fund with major support from Jon and Jo Ann Hagler on behalf of the Jon L. Hagler Foundation.