A trailer for William Shatner's documentary The Captains has been released. The film follows Shatner as he interviews previous Captains of the Trek Universe such as Patrick Stewart, Kate Mulgrew, Scott Bakula, Avery Brooks & Chris Pine who played Captain Kirk in J.J. Abrams’ Star Trek reboot. Shatner looks pretty entertaining as flogs the dead horse for what its worth. The Docu is set to premiere July 21st on the cable channel EPIX HD. Hit the jump to check it out.