The incident, which took place near The Camden Arms in La Belle Alliance Square, Ramsgate, Kent, was captured on CCTV released by the RSPCA.
It shows the animal's attacker seemingly dancing down the road with the black cat at arm's length. The animal is then seen colliding with the arm of another man.
The court heard that the attack would have physically and mentally traumatised the cat because it was swung with some force.
RSPCA prosecutor Rowan Jenkins said Lynne Jarvis, a neighbour of the cat's owner Michelle Buchanan, looked out of her window when she heard a commotion outside.
He said Miss Jarvis could hear "horrible laughter" and saw a group of youths swinging around what she thought was a cardigan. But when she realised it was next door's cat she went outside to remonstrate with the group, he said.
Miss Jarvis said other people with the man swinging the cat "were jeering and loving every minute of it", he said.
The man put the cat down after Miss Jarvis swore at him, the prosecutor said.
Miss Buchanan was told about the attack by her neighbour when she returned home from work later that day, the court heard.
In a statement read to the court, Miss Buchanan said Mowgli came home at about 9pm and seemed withdrawn but physically fine.
"He seemed lifeless. I would say really, really sad," she said.
Since the incident the cat was too frightened to go outside and his behaviour dramatically changed, she said.
CCTV of the attack was seen by a vet who said the cat would have suffered physical and mental trauma from being swung at such force, the court was told.
On November 11 last year Richards attended Margate police station voluntarily with his solicitor and gave a no-comment interview to RSPCA inspector Caroline Doe, the court heard.
Richards gave the RSPCA permission to search his home but nothing was found to link him to the attack, magistrates were told.
Paul Goldspring, defending Richards, said three other names of people who could be the man captured on the CCTV were given to the RSPCA inspector, as well as Richards's.
There was no evidence which would identify the man in the video as his client which meant there was no case to answer, he told the court.