> He approached them first. Watch the full livestream. The Chinese group approaches the piano first, and one woman even dances along to his playing. Later a f

> He approached them first. 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.