Slater has counter-sued for defamation on the basis of comments Craig made about him in a press conference and media interviews.
The press conference was also played, in which Craig repeatedly accused "the dirty politics brigade" of defaming him.
He named Slater only when he announced that he would sue him and ask for damages of $650,000.
Slater's lawyer, Brian Henry, asked Craig about a booklet he produced at the same time, asking how much was spent on it, and how widely it was distributed.
Craig said it was "broadly distributed" and he spent $287,000 on printing and distributing it to about one million households.
Henry asked Craig if he accepted that he created "a new media cycle" by holding a press conference and distributing the booklets.
Craig said that he did, but when asked if he accepted the aim of the media and Whale Oil was to find the truth, he said he did not.
He said that the main aim of media was "to sell newspapers and stories".
"Whale Oil also has a political agenda."
It was the fifth day of the judge-alone trial.
Craig alleged Slater defamed him by saying he was "a sexual deviant" and harassed women.
Craig's allegations relate to an alleged relationship with his former press secretary Rachel MacGregor.
MacGregor pursued a sexual harassment case against Craig after resigning in 2014, and was awarded $128,000 in damaged by the Human Rights Commission.
The trial is expected to last three weeks and Craig's wife, Helen, is due to give evidence on Monday.
