"Each of you had an active sex life and would explore new and different sexual behaviour with each other," he said.
"In that context, the current offending occurred.
"Each of you say that you undertook the activity primarily because you thought that the other was interested in doing so."
The former couple was each handed a four-month prison sentence, wholly suspended on a two-year, $2000 good behaviour bond.
Judge Stretton also ordered that they each complete 300 hours of community service within the next 18 months.
Rebecca Thredgold, wearing a face mask, left court with a supporter, who physically pushed away a photographer and told media "you're ruining my life".
Leaving separately to his ex-partner, Kevin Thredgold covered his face almost entirely and swore at the media.
The court heard earlier this month the videos were never distributed and were only discovered by police after Rebecca Thredgold handed over hard drives during an unrelated investigation.
Judge Stretton said the former couple each pleaded guilty and accepted responsibility for their part in the events depicted in the video and the case has brought them "extreme embarrassment and shame".
He said police who viewed the video reported the dog did not appear to be in pain or harmed by the couple's actions.
However, the judge said the charges were serious because they present an "affront to public dignity and norms of human behaviour".
