The show started as an independently released podcast from 2011 to 2013, before being picked up as a professionally produced web video series by Thing X in 2012, continuing after the site merged with Adult Swim's website in 2013.

[1] Although reviewing films remains the central conceit, the focus of the series quickly shifted from a mockery of amateur podcasting and YouTube criticism to an extended, improvisational character study of the duo.

Later seasons have seen Tim lose interest in reviewing movies, instead creating a TV show, Decker, and starting a rock band, Dekkar.

Tom Cruise Jr. died shortly after birth after Tim refused to have him vaccinated, and his death led to their marriage rapidly spiraling apart.

Later, after Toni’s son Matt is shot and killed, they reconcile, with Tim taking the name of "Newman Heidecker" owing to a misunderstanding while getting his marriage license certified.

Despite his obvious lack of critical insight Gregg believes that On Cinema should be devoted exclusively to "the movies" rather than Tim's personal life and views.

Gregg produces many of the show's recurring segments, including "Popcorn Classics" and "On Cinema On Location", and plays Special Agent Jonathan Kington on Decker.

He is mainly quiet and withdrawn, actively avoiding confrontation, redirecting almost every conversation into a movie reference and regarding real-world events and documentary films as pointless distractions.

Gregg continues to stubbornly insist that San Francisco was the location of Star Trek II, briefly leading to him being ejected off the show in season 3.

In the third special, Peyton Reed comes on to promote his new film Ant-Man and announces that Gregg has been cast as a minor character in the movie, which upsets Tim.

Tim starts a rock band named Dekkar with another member, Axiom, in season 7, and releases their debut single "Empty Bottle" on the show.

Dr. San prescribes Tim a "nutritional vape system" in season 8, which replaces all meals and food with an electronic cigarette full of supposed nutrients.

A fire is started in the storage unit one night after Tim's vape pen overheats, burning the entire facility down, including the VFA.

In season 9, Tim hosts the Electric Sun Desert Music Festival in Apple Valley, California, where Dr. San gives out free samples of his vape system, resulting in 20 deaths and over 100 injuries.

Frustrated with his attorney Mark Dwyer, Tim decides to represent himself and proceeds to threaten the prosecution led by Vincent Rosetti and its witnesses and falsify evidence.

In the season finale, an irate Tim destroys the set, insults the Delgados, and announces his campaign for district attorney of San Bernardino County against the incumbent Vincent Rosetti.

During the fifth Oscar Special, Mark is locked tight into a standard diving dress while doing an impression of Matt Hooper from Jaws, but is knocked out from asphyxiation and enters a coma.

Tim breaks into the studio with militant conspiracy theorist Michael "LaRue" Matthews, to wrest control and promote QAnon theories.

[13] Tim's failed campaign for district attorney is covered in Mister America, which was distributed by Magnolia Pictures and released on October 4, 2019, at Beyondfest, held at Grauman's Egyptian Theatre.

Gregg leaves his car running throughout the special, causing the entire production crew and wedding party to fall unconscious to carbon monoxide poisoning, leading to two deaths.

The ninth Oscar Special takes place at the planned site of the HEI Ranch, Tim's proposed business and media center, located on a remote stretch of land near Apple Valley, California.

Tim has a doctor lethally inject him in order to prove the grain water unlocks immortality; although it did not kill him, he remained unconscious and had to be hospitalized.

The service, consisting of a Dropbox folder full of public domain movies, unintentionally includes dashcam footage of the VFA Tour Bus crash, which appears to show Tim intentionally swerving the car into traffic in a suicide attempt, before turning into a ditch.

Gregg starts trying to bond with Kaili after finding out she is a fan of Harry Potter, giving her presents and tickets to see the movies with him, which she doesn't follow through on.

On the last day of AmatoCon, Tim gives a confusing and ultimately aborted keynote address on the “gift” of his disorder, in front of a sparse and indifferent audience.

Joey temporarily stuns Gregg and attacks Tim, who staggers back into the convention center with his face covered in blood, tells Toni that the Amatos are responsible for Matt’s death, and collapses to the ground.

Gregg intends to make the place a tourist attraction, while Tim, now known as Newman Heidecker, moves in with Toni following financial difficulties.

[1] The show has a dedicated cult following of fans who interact with the storylines via social media, often taking sides as "GreggHeads" or "TimHeads" in the frequent personal conflicts between the hosts which are often only tangentially, if at all, related to films or cinema.

[10] During the annual live Oscar special, Tim and Gregg both frequently provide interactive elements via online polls for fans to vote on.

Heidecker and Turkington also started Decker-Con, where new episodes of Decker are shown to fans and the cast appears as their On Cinema characters to field questions.