New videos from Alan Jackson and newcomer Katrina Elam make their world television premieres Thursday (Aug. 12) on CMT's Top Twenty Countdown. Jackson's video for "Too Much of a Good Thing" is already available for viewing at CMT.com. It's the first single from his new album, What I Do, scheduled for Sept. 7 release. Filmed onstage at the Grand Ole Opry, the video features cameo appearances by Porter Wagoner, Josh Turner, Connie Smith, Jeannie Seely, Steve Wariner, Little Jimmy Dickens and others. Oklahoma native Elam makes her video debut with "No End in Sight," a track from her self-titled Universal South Records album set for release later this year. Top Twenty Countdown airs at 6 p.m. ET/PT.