LONDON – When the $ 1.4 million artwork began to pass through a crusher hidden in its frame, gasps were heard in the auction room. Around half, the crushing stopped suddenly and the top of "Girl With Balloon" seemed to have been saved.

But that pardon, according to Banksy, the street artist who created the work, and who organized the joke to destroy it, was not planned. In a clip posted on YouTube on Wednesday, Banksy suggested he intended the painting to be completely destroyed at the auction in London on October 5, but that the plan had been thwarted when the crusher unexpectedly got stuck.

In the clip, called "Crush the love", is shown to a man constructing the frame, with the face hidden by a hooded sweatshirt. "In the trials it worked every time", says a subtitle. The video then shows a copy of "Girl With Balloon" being completely crushed as it slid out of the frame.

The copy in the clip seems to have been printed on paper, while the "Girl with Balloon" that was sold at the auction was painted with spray on canvas, a harder material, which may explain why the shredder failed. Joanna Brooks, the director of JBPR, who answered questions from the media on behalf of Banksy, did not respond to phone calls or an email asking if the tests had been done in hard copies.

"It looks like paper is coming out, but there's a chance it might be fine linen," said Danielle Howe, who works at John Jones, a London-based linen supplier. But, he added, "it's hard to determine without looking at the work in person."

Banksy's joke caused commotion and fun, but it also led to a series of conspiracy theories about Sotheby's involvement. "Some people think that the auction house was involved, they were not," Banksy said. An Instagram post on Thursday to alert people about the YouTube clip.

Alex Branczik, Sotheby's contemporary art chief in Europe, also denied any collusion. In an interview with The Art Newspaper published on Wednesday, he said Sotheby's had asked Pest Control, Banksy's official authentication body, if the eye-catching frame could be removed before the auction.

"Pest control said very clearly: the framework is an integral part of the work," said Mr. Branczik.

He added that a "third-party conservator" had inspected the frame but had not noticed the crusher. "You direct what you see, it was more like a sculpture," Branczik said. The conservative did not disarm the framework, he added.

The buyer of the work has kept the piece. Now it's called "Love is in the bin", after Pest Control issued a new authentication certificate for the job.