The period of Mr. O’Brien’s life framed by the film is not exactly underexposed. In January 2010 he very publicly declared (in an open letter addressed to “People of Earth”) that he would not go along with a plan by NBC to push his “Tonight Show” to 12:05 a.m. and insert Jay Leno at 11:35 p.m. He hosted his final NBC broadcast later that month.

Though his severance agreement with NBC (he was reported to have received $32 million) barred him from the airwaves until the fall, Mr. O’Brien announced that he would give a series of live performances, April through June, called the “Legally Prohibited From Being Funny on Television Tour.”

The tour appeared to be good therapy for Mr. O’Brien, who got to live his rock-star dreams by ripping television executives and performing his parody of “On the Road Again” for paying crowds.

But at the outset of the documentary Mr. O’Brien admits that he is “very angry about the way that I was treated” by NBC, adding that he is “the least entitled person you’ll meet in the world.”

The 90 minutes or so that follow seem dedicated to tearing down Mr. O’Brien’s assessment of himself, as he is relentlessly pummeled by the expectations of his fans and the rigors of the road. He is seen snapping at his wife, Liza; his assistant, Sona Movsesian; and the “30 Rock” actor Jack McBrayer, whose smiling Southern countenance collapses when Mr. O’Brien serenades him with a piano tune called “You Stupid Hick.”

By the time Mr. O’Brien reaches the Bonnaroo festival in Manchester, Tenn., in June, the temperature and his temper are at full boil. Frustrated by the demands of the festival’s organizers and told that his ordeal will be over soon, Mr. O’Brien replies, “I know people keep saying that, but that’s what they said to Anne Frank.” (When someone off -camera reacts to the comparison with shock, Mr. O’Brien adds, “We both took a stand.”)