No, he's having fluent and meaningful exchange of words with those interviewees.
> Chinese speaker here
You're definitely not a native speaker.
> almost like mocking the Chinese staff
I'm not sure why you interpreted it that way but there's absofreakinglutely no mocking people in there, hey.
All of those whom he interviewed were speaking Mandarin with different degrees of accents and apparently the guy has some pretty decent level of command of the language so he can still converse with most of them no problem. The last one he interviewed (starting from 03:30) spoke with a heavily accented version of Mandarin so even I had to pay attention to understand like, 80% of what he was saying; the reporter probably had issues understanding him as well so he just smiled and nodded. Overall I found the reporter's usage of Mandarin as well as his interaction with others to be very natural.
I am a native Mandarin speaker.
I think he's just trying to sound excited, to make the video more compelling.
I think it's perhaps because the BBC does a lot of educational material aimed, at least partially, at children and schools, and the presenters are trained to be very exaggerated and enthusiastic in their reactions. Experts like scientists and engineers can be quite placid in their delivery, and so the presenter's job is to make whatever it is they're talking about seem more "exciting". E.g. some engineering project, scientific experiment, historical fact, etc.
Maybe a bit of pandering, but I think he is just trying to be polite, but I don't see any sign of mocking.
But from a certain point of view(where you assume this is just a normal conversation between two people), i can see what you mean.
[1]"Man of Race-or-Country Y is exaggerating something in our language? Race-or-Country Y must be looking down on us!"
Sort of like mocking hick accents in the US, real funny until you're talking with someone who actually has a hick accents, and then it's just kinda mean.
Don't think there's any malice there, must be hard to context-switch between speaking a non-native language while interviewing for a foreign audience.
EDIT: if you've watched other BBC productions, the level of enthusiasm would be familiar. I think it is a BBC company culture/style thing. Drawing a blank at the moment, had someone very specific in mind, but maybe anything by Clare Balding, Sue Barker or Lizo Mzimba though none of these are the person I have in my mind...
(I'm a native Mandarin speaker.)
I agree with you that this reporter really didn't add to the conversation. Like you said, it is more of repeating/exaggerating.
Programs like this can be paid to make with purpose of showcasing a government project instead of actual "reporting".