The violent altercation between police and a Sydney youth during this year's Mardi Gras parade began when the youngster was arrested for allegedly pretending to kick a woman, a court has heard.

The incident in which Jamie Jackson Glenn Reed allegedly attacked an officer and was then grabbed by the throat and twice forcibly thrown to the ground generated widespread publicity and anger towards police, due largely to videos of the incident posted on YouTube.

Mr Reed, 18, is now facing charges of assaulting police, resisting arrest and using offensive language in the Downing Centre Local Court. He is countering with claims of police brutality.

One of the two police involved in the incident, Constable Leon Mixios, told the court that he had been undertaking crowd control duties in a small courtyard near the corner of Oxford and Riley streets on the night of the parade when he saw the youth, wearing only small black shorts, "half skip and half run" towards a young woman.