Buzzard-Quashie, from London, was in poor mental health and had been reported missing by her family on 3 September 2021.
She was tracked down to the gateway of Althorp House stately home by police officers who checked on her welfare then followed her car for 15 minutes.
The footage showed officers in a third police car throw metal spikes in front of her Range Rover causing her to pull over.
She was told she was not under arrest, and was seen walking away along the A428.
Minutes later two officers forced her to the ground for failing to stop, whereupon she said her face was pushed into stinging nettles.
Buzzard-Quashie told the BBC she believed Northamptonshire officers had detained her to remove a graphic CCTV recording that she had recently received from the Met Police, which she had in the boot of her car.
It showed her using a custody toilet at Hammersmith Police Station in west London in March 2021. She had made a formal request for the footage to be released by Scotland Yard.
She claims she was wrongfully arrested by the Met for malicious communications after posting on Instagram some of the racist messages people had sent her. She was not charged with any offence.