Los Angeles (CNN) -- Kanye West and Kim Kardashian are accusing a YouTube co-founder of illegally publishing video of their engagement party to boost his new "foundering" website.
A lawsuit filed Thursday by the celebrity couple blasts Chad Hurley, accusing him of secretly recording West's surprise proposal to Kardashian in the middle of San Francisco's AT&T Park on October 21.
The video shows West kneeling near second base to ask Kardashian to marry him while a large orchestra plays in center field. The leak diminishes the value of the video of the event that Kardashian and West own, the suit said.
Hurley "finagled entry" into the birthday party that West threw for his girlfriend, although only "several dozen people" were invited, the lawsuit said. Although he tagged along with someone who was invited, he was permitted to stay "only after giving his word -- including in writing -- that he would not publish any aspect of the event." The court filing includes a photo of Hurley purportedly holding the signed confidentiality agreement in his hand.
"Immediately after giving his word to honor the condition required for his attendance at the event," Hurley posted the shaky video on MixBit, a video sharing website owned by his San Mateo, California, company, it said.
The lawsuit slammed Hurley, 36, as a failed entrepreneur who leaked the video "out of desperation."
"Despite his extraordinary financial success in creating YouTube, which was sold in 2006, Hurley has ever since sought his 'second act,'" the lawsuit said. "This has become exceedingly elusive to Hurley."
It cites his failed Formula One racing team and his "Web service named Zeen, which also failed and has been slated for closure in 2013."
His newest venture -- MixBit -- "also quickly ran into trouble" after launching in August, the lawsuit contends. "Following a lackluster launch and unsuccessful ensuing debut, Hurley sought to salvage MixBit from its dour beginning," the suit said.
"An opportunity to do so appeared to Hurley when he learned of the October 21, 2013, event featuring West and Kardashian," it said.
The video is titled "PLEEESE MARRY MEEE!!! Congrats Kim and Kanye!"
It is still posted on the website, and the counter indicates it has been viewed 1.6 million times.
Hurley knows better, the lawsuit said. The terms of service on his own website warn users against posting any video that would violate copyrights, it said.
"Undeterred by the contractual restrictions to which he had just agreed, Hurley opted to exploit and capitalize upon the extreme public interest he knew would attach to the event, in order to boost the fortunes or his underperforming business venture," the suit said.
Hurley and his company did not immediately respond to CNN requests for comment on the lawsuit.
CNN's Doug Hyde contributed to this report.