Not sure why the person filming it should necessarily be flouting the law.
Although sex in public in the UK, is considered an offence under 'public decency' - just as one can't simply whip one's cock out and start masturbating in a shopping centre, for example.
However, these are 'staged' videos, with adults who have consented to being filmed - under the 'guise' of 'covert filming' - indeed, many girls appear in numerous 'editions' and are, otherwise, sex workers who are more than delighted to receive extra payment, whilst retaining their anonymity.