The mother-in-law of the police officer caught on tape pinning a Kununurra woman down and punching her in the head has come to her son-in-law's defence.

The video, published by WAtoday on Wednesday, shows two police officers attempting to restrain a woman in front of a group of noisy onlookers.

One of the officers mother-in-laws told Radio 6PR her son-in-law was upset by the video and claimed what it didn't show was that he was bitten during the incident and required hospitalisation for concussion afterwards.