A Northamptonshire police officer shouted in an elderly woman's face and forcibly pulled her out of her chair, a misconduct panel heard.
He then laughed as he screened footage of the incident to his colleagues back at the station.
Special Sergeant Alec Bedford, 26, was disciplined yesterday (April 18) at a hearing at Northamptonshire Police Headquarters, in Northampton, for his part in a "distressing" incident involving an 87-year-old woman and her husband in their own home.
Chair of the misconduct hearing Geoffrey Payne said: "The trust the victims involved in this case had in Northamptonshire Police is now gone.
"This was a life-changing event for the couple and one that hurts the reputation of the force."
Special Sergeant Bedford did not attend his disciplinary hearing.
He was one of three officers called to the house in the Daventry area in July 2015 following a two-week-old report of domestic violence at the property.
The resulting incidents at the elderly couple's house were filmed on one of the officer's body-worn cameras.
The 87-year-old woman protested when the officers said they would arrest her 90-year-old husband and tried to use a telephone to call their daughter.
Mr Payne said: "The footage shows Bedford shouting 'sit down now' very close to the woman's face, before forcibly pushing her down into her seat.
"It was then that the woman caused an action that leaves a scratch on Bedford, to which Bedford says 'you'll be arrested for assault in a minute if you're not careful'.
"[Another, higher-ranking officer] then tells Bedford to 'lock her up'. After a moment, Bedford replies 'yeah, that's it', then pulls the woman to her feet and tells her she is under arrest."
The footage then shows Bedford alternating between restraining the elderly woman and attempting to take her phone from her.
The panel then heard how, later that week, an officer saw Bedford screening the footage of the 'distressing' arrest to his colleagues.
Mr Payne said: "He was loud, laughing and not taking any notes. It is apparent there was no reason for the other officers to see this footage and that it was an attempt to be sensational."
But Bedford was then caught screening to footage again to another officer three days later - by the 87-year-old victim in the video.
My Paynes said: "When the woman and her daughter arrived at the police station to settle her arrest at her house, she found Bedford on the front desk showing the footage to his colleague.
"The footage shows two very distressed members of the public. This was entertainment in the loosest sense of the word and shows a very complacent attitude towards confidentiality."
Although Bedford later apologised for his behaviour, the panel found that his actions amounted to misconduct.
Mr Payne said: "This is a serious incident, but one that falls on the lesser end of the spectrum, as he did not leak the footage to a third-party. Additionally, he was instructed to arrest the victim by a high-ranking officer.
"However, there was a high level of culpability involved and considerable harm was caused to the victims."
Bedford was issued a final written warning, meaning any further misconduct over the next 18 months will put him at risk of dismissal.
Another officer at the incident was sanctioned at a separate hearing.