Joaquin Phoenix’s Joker is an unhinged anti-hero – but how hard was the Oscar-nominated star to work with?

Joker cinematographer Lawrence Sher, who was nominated for an Oscar on January 13 for best cinematography, unexpectedly found himself at the centre of a viral video in October, when the graphic comic-book film was first released.

We never see him in the video, which aired during Jimmy Kimmel Live! when actor Joaquin Phoenix appeared to promote Joker. But we hear about him. In the video, Phoenix is yelling at “Larry”, who's off camera, telling him to “shut up” with the “constant whispering”.

Sher is that Larry, he told Business Insider in an interview shortly after the video went viral. He explained the outtake originated as a prank on the movie’s director Todd Phillips, who was also received an Oscar nod on Monday. Sher has collaborated with Phillips on all of his movies since 2009’s The Hangover and Joker is their sixth film together. But the joke didn’t land on set.

Phoenix is “such a good actor that nobody even got it on set”, Sher said. “He played it too straight.”

But the film certainly landed with the Academy of Motion Picture Arts and Sciences.

Joker led the nominations with 11, including for best picture, director (Phillips) and actor (Phoenix). It was also a hit with audiences and grossed more than US$1 billion worldwide.

“I knew based on the script and the material that this was an opportunity I wanted to do,” he said. “We knew we had an opportunity to do a character piece and the nature of the structure allowed us to put more emphasis on ‘art’ than we’ve done before. With comedy, you do your best to make a funny scene. With Joker, there were opportunities to be more artful in composition and lighting. If we did that for The Hangover, it would take you out of the film.”

Sher also talked last year about what Phoenix was really like on the set, the controversy surrounding the movie’s graphic violence, and whether any comic books inspired the filmmaking process.