Sexual Images Online
If someone has uploaded sexual images of another person without their permission then they may be breaking the law, however this depends on the circumstances.
Prosecutable offences include:
If the video or photo is of a person under the age of 18 and is indecent - the police will become involved regardless of the circumstances.
Revenge porn is the publication of explicit material portraying someone who has not consented for the image or video to be shared - It is an offence to disclose a "private sexual photograph or film" without the consent of the person depicted, and with the intent to cause them distress. A person found guilty of this offence will face a fine or even imprisonment.
If the circumstances do not fit the above offence, i.e. there is no intent to cause distress if the photo/video is for example, on one of the social networking websites, you could speak to the administrator of the internet site who may remove the material.
Otherwise you would need to obtain a restraining order from the courts to order the removal of the material. You should seek advice from the Citizens Advice or a solicitor about this matter.
Showing video footage of you without your permission and there is no intent to cause distress:
If you are over 18, the footage needs to be classed as obscene (the legal threshold of what is obscene is quite high and would not normally cover what could be classed as merely offensive).
If you are under 18 then the footage needs to be classed as indecent before the police can become involved.