Christian has a lot of fortitude: he wants two tries at the American dream of success, and by golly, he may make it after all. A writer for the hit HBO series “Six Feet Under,” the charming, gay British expatriate is summarily fired at the end of a season, with the advice that he seek work on hospital dramas. Most folks would plunge into an early mid-life crisis, but not Christian. Instead, followed by a documentary crew who expected to record his last gig, he gamely researches his own film about Las Vegas showboys, putting himself through the grueling paces of tryouts and callbacks.