Remember when 9/11 was supposed to have changed everything? Well, it did for Amy Rice and her brother Andrew after their older brother David, an investment banker, went to work at the World Trade Center and never came home.</p><p>&ldquo;Andrew and I woke up to the political world that day,&rdquo; Amy Rice recalled. </p><p>Andrew was working in Toronto for the BBC. He quit, returned to the family&rsquo;s hometown of Oklahoma City and started a nonprofit. And then he ran for the state Senate. Last month his Democratic colleagues elected him as their leader for the 2011-2012 legislative session. </p><p>Amy, a cinematographer working in indie features, began to segue into documentaries. One sultry day in the summer of 2004, the phone rang. It was Andrew, watching the Democratic convention on cable. <em>You&rsquo;ve got to see this</em>, he said.</p><p>&ldquo;Do we participate in a politics of cynicism or do we participate in a politics of hope?&rdquo; she heard Barack Obama say. &ldquo;I believe that we have a righteous wind at our backs and that as we stand on the crossroads of history, we can make the right choices and meet the challenges that face us.&rdquo;</p><p>Like millions who heard those words, Rice realized she could be listening to a man who some day &mdash; 2012 maybe, or 2016 &mdash; would be elected the first African-American president. She and her producing partner, Alicia Sams, sought out the junior senator from Illinois and began filming him, collecting video that they hoped would come in handy in a few years.</p><p><strong>&ldquo;By the People: The Election of Barack Obama,&rdquo;</strong> airing 8 p.m. Tuesday on HBO, chronicles what happened next.</p><p>Obama unexpectedly jumped into the 2008 race and quickly recruited a cadre of young people willing to put their lives aside to elect him. Rice and Sams did much the same. The result is surely the most intimate view of the transformational effects of the Obama campaign as any documentary we&rsquo;re likely to see.</p><p>Yes, of course, the campaign turned an up-and-coming Democratic politician into an American legend, a Paris fashion icon, an African hero. But &ldquo;By the People,&rdquo; as its name suggests, also tells the story of the ordinary people who took part in that epochal event and were themselves changed.</p><p>The first scene in the movie shows Obama in a &ldquo;war room,&rdquo; watching returns come in during the 2006 mid-term elections.</p><p>&ldquo;I love elections,&rdquo; the non-candidate tells Sams, who&rsquo;s standing off-camera. &ldquo;They&rsquo;re even more fun when you&rsquo;re not on the ballot.&rdquo; </p><p>And that&rsquo;s pretty much how Obama is whenever the camera is on him. (Michelle Obama is seen from time to time here, too, but in much more controlled settings.) Almost all the footage of Barack Obama seen in &ldquo;By the People&rdquo; could have come from C-SPAN. The takeaway, I guess, is that there hasn&rsquo;t been a time in his public life when he wasn&rsquo;t as cool as the other side of the pillow.</p><p>The second scene in the film is in Des Moines, five months later, nine months before the Iowa caucuses, where a campaign worker named Ronnie Cho is calling voters, building support for the newly declared candidate. Cho, whose parents emigrated from South Korea, and who remembers living in a car with them for more than a year, is the face of the Obama transformation. Change is a palpable thing for Cho, who gets more and more responsibility during his 21 months with the campaign. </p><p>It is these stories, from those on Obama&rsquo;s Iowa team, that give &ldquo;By the People&rdquo; its appeal, its sense of motion. Obama is so relaxed, you have no idea that, over the course of the film, those two women with handheld cameras have been joined by thousands of media and onlookers and power-seekers around the world. But you definitely get the sense of the drama whenever the camera turns on Cho.