A police officer was caught on videotape punching and kicking a man in a "disgraceful lack of control" during an arrest, a court was told yesterday.

Keith Empsall, 42, a constable in the West Yorkshire force, allegedly struck his victim repeatedly in the face before kneeing him in the groin while handcuffing him by a police car.

The incident in June last year in a residential area of Wakefield was recorded by an amateur cameraman who was documenting student life in the area.

Mark Goodwin told Leeds magistrates' court how he was alerted to the altercation outside his home by his girlfriend. He looked out to see PC Empsall, who denies common assault, and a second police officer dealing with 27-year-old Christopher Wilson as he was arrested while drunk in connection with vandalism on a car.

PC Empsall was seen grappling with Mr Wilson, kicking him in the groin and striking blows with such force that he had to move to follow up each punch, the court was told.

Mr Goodwin said: "There were three punches with the left hand to the face of the man. The police officer had to keep up with him after each blow because the man was being knocked back. He had to move forwards to keep up with him. And then he was pushed hard up against the police car and handcuffed behind his back. As he was being handcuffed there was another kick or a knee delivered to the man.

"The same officer then grabbed the man in question by the hair and dragged, or attempted to drag him by the hair towards the second police car, but he lost grip of the hair so he led him across by the arm to the car."

Mr Goodwin said he used his video camera as one of his hobbies and as part of his interest in art. He said: "I didn't press record because I saw some bad conduct – I was just documenting student life on that street. I just filmed it out of general interest."

Jonathan Carroll, for the prosecution, said police had a right to use reasonable force when arresting suspects but that PC Empsall had gone far beyond acceptable behaviour. Mr Carroll said: "It is a disgraceful scene of improper police conduct, a lack of control by a police officer of himself, bullying and throwing his weight around."

Mr Goodwin, a music student, told the court that he had made £7,000 from the one-minute video after signing an agreement with GMTV to share the rights to his film.

He denied suggestions that he had a financial interest in seeing PC Empsall convicted by making the footage a "police brutality" video and maximising his income.

The incident took place after Mr Wilson, who has previous convictions for burglary and theft, had spent the evening drinking with friends in his flat. They had shared a bottle of Southern Comfort. Mr Wilson said he could not remember if he was aggressive towards the police officers. He said: "I can't remember a great deal about that night. I can remember being punched in the face and then being pushed into a car."

He said he woke up the next day with a pain in his face. "It was on the right side of my jaw. I remember because I complained to everyone about it. It felt like I'd been hit with a truncheon or something."

The case continues.