https://www.met.police.uk/advice/advice-and-information/ph/p...
The police are public officials. The law in question says it is not illegal for citizens to record public officials, including police officers. I would imagine this is partly to help citizens keep their police force accountable. So this person was well within their rights to 'not have a private conversation' with the police officer.
But it's a very different situation from, say, filming someone who does not wish to be filmed, or harassing someone in public by filming them and then posting online publicly, and pretending it's fine just because you were in a 'public place'.
The technical legality of the situation aside, given that these individuals politely (initially) requested their faces be not shown on public youtube videos (for profit no less), and this person made no effort to even blur at the very least, then I have a hard time finding right with him.
We're not even talking about whether a private individual should have the right to film such that this might be presented as evidence in a court of law if required. So this is not a free speech issue. This person is simply putting it on youtube for money. Without reasonable consent. Yes not everyone in the video needs to give consent, as this can be implied if they walked through a scene and the recording was 'non-hidden'. But these people explicitly denied consent. There must be some sort of GDPR thing at play here at the very least.
Apart from that, it's sensible to understand if you're just background on somebody's recording in a public space and don't want to appear, just walk away.
He approached them first. They declined participating and in about 3 minutes one woman approached him back and asked not to put their faces on TV - that's when the whole fuss had started.
Watch the full livestream. The Chinese group approaches the piano first, and one woman even dances along to his playing.
Later a few more people join the Chinese group, one of which appears to be a producer as he's handing out scripts. The piano player approaches the Chinese group to say hi to the new members, and suddenly they have a problem with him filming.
The simplest explanation is the most likely - they're a Chinese TV crew who want to use the piano, but they don't have a commercial filming permit and/or UK working visas.