Surveillance video from Iran circulating on social media Tuesday appears to show two missiles hitting the Ukrainian passenger jet downed over Tehran, fired approximately 30 seconds apart, providing new information about the tragedy that killed 176 people on the plane.

The video was verified by Storyful, a social-media-intelligence company owned by News Corp, parent of Wall Street Journal publisher Dow Jones. It raises new questions about how forthcoming Iranian authorities were when, after three days of denial, they admitted...