The video, obtained by The Sun, shows a man wearing a mask and holding an arrow in his hand, claiming to be trying to assassinate Queen Elizabeth of the royal family, according to AFP.
The man is speaking vaguely in front of the camera, introducing himself as an Indian Sikh and trying to "avenge" the notorious massacre of Sikhs during the British Raj in 1919.
According to the report, the accused was arrested by the armed police from Windsor Castle area of West London on Christmas day but 24 minutes before that the said video started circulating on social media.
London's Metropolitan Police say officers found an arrow during a security breach and that a 19-year-old detainee has been receiving psychiatric treatment.
He said that the video was being reviewed after the arrest of the citizen.
The statement said that at 8.30 am on Saturday, security was activated within minutes of the accused's attempt to enter the Castle Ground so that he could not enter any building.
The incident took place when the Queen was in Britain to celebrate Christmas, accompanied by her eldest son Charles and his wife Camilla.
In the video, a masked man says he wants revenge for the Jallianwala Bagh massacre.
It may be recalled that in April 1919, British troops opened fire on thousands of people, including women and children, in the northern city of Amritsar.
It is unknown at this time what he will do after leaving the post.
Including the number of deaths in the video, the accused said that it was also revenge for those who were killed, tortured and discriminated against because of their struggle.
In a short message in the video, he also gave several references to Star Wars while predicting his imminent death.
According to the report, a person attempting to enter the royal palace has been subject to the provisions of the Mental Health Act, which requires authorities to detain anyone in England and Wales and treat them for mental illness without their consent. Is allowed.
Under the law, detainees are considered a threat to themselves and others.
