Two decades ago, the 9/11 Commission found al Qaeda acted alone in the Sept. 11 attacks that killed nearly 3,000 Americans, but victims' families say that isn't true. They point to a newly-released video filmed outside the U.S. Capitol two years before the attacks, and other evidence, as proof. The families are now suing Saudi Arabia, claiming its government provided crucial assistance to the hijackers and planners of the attacks.