The 25-year-old Canadian actor appeared to be highly intoxicated and stumbling as he relieved himself over the carpet at LAX.
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Shocked onlookers watched as he continued, seeming oblivious to his surroundings, ignoring urges to stop. Policemen soon arrived, dropped him to the ground and handcuffed him.
The apparently heavily-inebriated star - who has a court date for January 7 - celebrated his birthday on New Year's Eve and had previously denied the charges prior to the video emerging.
The incident came after he was thrown off his flight for causing a disturbance on board and deemed "too intoxicated to fly".
He is also due in court on January 17 to answer to alleged crystal meth and cocaine possession charges after an arrest last month.
His spokesman told TMZ that Pelletier "realises he has issues and will be entering a treatment programme for addiction in the near future".