Before “Inside Deep Throat” even begins to unravel its delicious plot, it becomes clear to the solitary trench-coat-swathed man that this film won’t provide the fulfillment he’s seeking. Nervously shifting in his seat, he audibly sighs and walks out after five minutes of compelling documentary footage and Dennis Hopper narration. (His loss.)

“Inside Deep Throat” is hardly an excuse to recycle grainy reels of Linda Lovelace engaging in titular oral acrobatics, but rather a fervent war cry for the freedom of expression. The film packs a walloping punch as it careens through 90 minutes of dizzying editing and hilarious anecdotes about the 1972 porno classic “Deep Throat.” And there’s sex.

Tightly packed into an NC-17 marvel, the original “Throat” is a cultural artifact for an American Studies major to lust for — as a critical analysis of pornography and its social context, the film is nearly perfect. As the awkwardly delivered parental adage goes, “Sex is a beautiful thing.” Extending this exoneration to the world of cinema, “Inside Deep Throat” expresses reverence for pornography as an artful expression of humanity. While initially a hard concept to swallow, you’ll leave the theater longing for the golden days of porn, rife with Farrah Fawcett hair and Farrah Fawcett feminism.

After a hurricane of plot exposition foreshadowing political turmoil, the film humbles itself with charming introductions to “Deep Throat” alumni. First off, we see the film’s director, Gerard Damiano, as he waddles down his Florida street pregnant with a beer belly and tanned beyond comprehension. With a heavy New York accent, he unveils his past as hair stylist and pornographer.

Now virtually a chapter in the anthology of Americana, the film’s plot manages to shock present-day spectators as much as it did then. The mythology of the film centers around a woman with a crisis — she can’t find her clitoris. Frustrated by her pallid sex life, she decides to visit a doctor for guidance. Under kitschy wisdom, she realizes how she can reach sexual nirvana — thus the film’s title.

Shifting between the swampy accent of Damiano and the slimy cadence of Dennis Hopper, the audience becomes privy to the porno flick’s lackluster beginnings. Filmed under the decadent Floridian sun, “Deep Throat” was apparently conceived as a legitimate film with sex. Damiano is proud of his film’s puns (“Do you mind if I smoke while you’re eating?” asks a raven-haired porn star, who happens to be enjoying cunnilingus). For the film’s protagonist, he opted for a talented actress — or, rather, an actress with the unique talent fulfilling the promise of the title: Enter the accidental iconoclast Linda Lovelace.

Armed with meticulously picked eyebrows and a cuddly cat named Adolf Hitler, Lovelace joined Damiano in Florida to film history. Melting a phenomenal soundtrack of ’70s music over revealing images, “Inside Deep Throat” captures the zeitgeist of an era with deft ease. The documentary ferociously exhibits the original porno as a polemic for a sexual revolution, using everything from Lovelace’s beach-side chat on sexual frustration to her climactic orgasm (which Damiano artfully illustrates by splicing scenes of a space rocket take-off).

The documentary, of course, exploits a bevy of arguments on sexual liberation and freedom of expression. Cultural icons such as Dr. Ruth Westheimer and Hugh Hefner offer overused discourses on the burgeoning sexuality of the time. One woman praises the use of semen as a kind of age-defying makeup (“It’s full of babies!” she squeals). However, as the audience is quickly reminded, “Deep Throat” wasn’t all fun and games. Predictably, a political firestorm ensued.

The documentary looks at the Nixon obscenity rulings and the subsequent banning of “Deep Throat” from New York theaters as a critical weighing of the First Amendment. All those involved with the 1972 film were indicted for indecency, and throat-tickler Harry Reems was sentenced to a prison (charges were later dropped) for his high-profile role in the film. At this point, “Inside” changes scope and instead becomes overtly political — though Lovelace swears ignorance (“What’s anarchy?” she numbly moans when asked about censorship and free expression).

While fluidly alternating between musing on the artfulness of pornography and larger issues of free speech, “Inside Deep Throat” never loses its pace or potency. But on the same note, it never really congeals its bouncing concepts into a coherent flow. It may not be as well-crafted or intelligent as “Boogie Nights,” but “Inside Deep Throat” doesn’t need to be. Bailey and Barbatos create a film with the instant gratification of any good porno. The movie is slick, gorgeous and relentlessly entertaining.