But how Millane died is very much disputed and will be pivotal during the murder trial, which began yesterday in the High Court at Auckland.
"They were plainly comfortable in one another's company that evening", he said.
22-year-old Millane was last sighted in Auckland, New Zealand in December 2018.
The film showed them meeting outside the Sky City casino, drinking at a succession of bars and entering the CityLife hotel where the defendant, who can not be named for legal reasons, was living.
Ms Millane is last seen alive leaving the lift at CityLife at 9.41pm, heading towards the defendant's room about four hours after they first met.
He then messaged another woman to confirm a date he had arranged earlier on Tinder, meeting her at a bar.
He said his team had looked at hundreds of hours of film captured over six days.
CCTV cameras filmed them walking through the CBD to The Bluestone Room where they settled at a small table, talking and kissing.
Grace's parents David and Gill Millane, from Wickford in Essex, watched as the court was shown CCTV of Grace taking a picture of a Christmas tree.
He then searched for porn online and took photos of Grace's dead body before he went on a second Tinder date, prosecutors said.
Later that day, he placed the body in a suitcase and drove it to Waitakere Ranges where he buried her, the jury heard.
The pair shared three jugs of margarita and sangria and left the restaurant about 8.30pm, at this point having spent almost three hours together.
About an hour and a half later, about 7.15pm, they left SkyCity and walked down Federal Street to Mexican Cafe on Victoria Street.
McCoubrey said the Crown case was that Millane died in the defendant's apartment due to sustained neck pressure.
Backpacker Grace ended her Tinder date arm in arm with the accused.
However, McCoubrey said, the accused went on another Tinder date while Millane's body was still in the apartment.
"I felt something was weird that she was on a date with a manager of an oil company, but due to being tired I didn't want to express this".
Prosecutor Robin McCoubrey told the jury the accused had strangled and murdered Grace Millane.
Thinking it was the man's own birthday, Grace's friend told police she had thought that to get very drunk "is a weird thing to do with someone you don't really know". "Bet it's like the top floor".
The Crown has alleged that the defendant strangled Ms Millane during rough sexual intercourse.
Mr McCoubrey told the court that the accused initially told the police he had met Ms Millane for a drink before parting ways with her, but then changed his story, saying he and Ms Millane went back to his apartment where they engaged in "rough sex".