A bus driver sent a video purportedly showing child abuse to his partner and others "for awareness", a court has heard.
Dido Massivi, 61, allegedly sent the video to his long-term partner Jennifer Hodge in February last year.
Mr Hodge then sent the video to her sister who is a police officer but did not take the matter further, the Old Bailey heard.
All three deny charges relating to indecent images of a child.
Giving evidence from the witness box on Thursday, Mr Massivi described how the video was sent to him by a colleague.
But when he opened it, he saw it was "very bad", the court heard.
Asked by defence counsel Lefi Tsiattalou why he sent it to his partner, Mr Massivi said: "It was about awareness. She (Ms Hodge) said she would look at it."
Mr Massivi told the court Ms Hodge said she was going to see her sister to "speak to her about the video because she wanted to report it".
The court heard how Mr Massivi sent the video to another colleague, saying: "This man needs to be caught."
Taking the video to police himself "did not come to [his] mind", he told the jury.
'I was upset, shaking'
Ms Hodge told the court she only opened the video the day after her partner sent it to her.
Giving evidence, she said: "It was disgusting. I threw my phone in the shock of it. I was livid, upset, shaking - in tears.
"My sister is a police officer, I wanted to find out about the platform it was on. I couldn't understand the nature of how it was allowed.
"I thought she might know a little bit more than me, then it could probably get taken down."
She added: "I wanted to try and get this sort of thing off the platform that it was on."
Mr Massivi, of Brent, north-west London, denies two counts of distributing an indecent photograph of a child, and one count of possessing an extreme pornographic image portraying a person having sex with a horse.
Ms Hodge, 56, also of Brent, denies distributing an indecent image of a child.
Ms Williams, 54, from south London, denies possessing an indecent image of a child in February 2018 and corrupt or improper exercise of police powers and privilege. She denies seeing the video.
The trial continues.