What is the last name of the person the Dixie Chicks are embarrassed come from Texas?
The film opens during the Dixie Chicks' 2003 Top of the World Tour, discussing the Dixie Chicks' superstar status prior to the incident at their London show.  They had sold more albums in the United States than any other female band in history. With the release of their 2002 album Home, they were again at the top of the Billboard Charts. The new single from that album "Travelin' Soldier", a sensitive depiction of a soldier's life during the Vietnam War era, and the young woman who waited for him, finding he was killed in battle, had peaked at #1 on the US Billboard Hot Country Songs Chart.
The film then cuts to a scene from the Dixie Chicks' March 10, 2003 concert at the Shepherd's Bush Empire Theatre in London, England. The atmosphere in the European audience is of dramatic opposition to the announcement from United States President George W. Bush's authorization of the invasion of Iraq.  Approximately 1 million people had recently demonstrated in London against the impending war. During the introduction to their song "Travelin' Soldier", Natalie Maines, a Texas native, says:

The Guardian, a major English newspaper, published Maines' statement as simply "Just so you know, we're ashamed the President of the United States is from Texas." Shortly thereafter, the U.S. media picked up the story and controversy erupted. Conservative groups in the U.S. rallied against the Dixie Chicks and a firestorm of anger and criticism followed.
The film shows the band's reaction to the open hostility, political and corporate backlash, and physical threats directed at the group. The band did not expect such a strong reaction, and they are unsure if they should "shut up and sing", apologize, or stand by their convictions and let more sparks fly.
Bush