A six-minute clip of Tulisa and former boyfriend Justin Edwards, known as DJ Ultra, was posted online last week.
Tulisa is currently suing the DJ for damages, claiming a breach of privacy and confidence.
But appearing in court, Justin insisted that he didn't leak the film, calling it "ungentlemanly" behaviour, the Daily Mirror reports.
He told the judge that Tulisa had "persuaded me that we should film ourselves" and suggest that filming took place on the singer's phone.
Speaking out over the tape last week, Tulisa said: "I am devastated, heartbroken."
"When you share an intimate moment with someone that you love and trust you never imagine for one minute that footage may at any point be shared with the rest of the UK."
She added: "This is the person, Justin Edwards aka Ultra, who is my ex-boyfriend, that has put it online, who is the other person on the tape."
In court, an injunction over the video was also extended, banning it from being posted online or shared.