I don't know the context of this video of NHS nurses talking to a pregnant mother. They are saying her baby will be given a PCR test as soon as it is born. She's saying she doesn't want this to happen. They say they will report her decision to Child Social Services. The father seems to be the one filming the exchange. The question is why are they trying to test a baby?
As far as I can see there is no general rule in the UK NHS that all newborns should be given SARS-CoV-2 RT-PCR tests. They are tested for various rare but very serious disorders which seems sensible, Covid isn't on the current list.
So, my guess is that the mother has tested positive. I believe that to get treated in an NHS hospital you have to have a RT-PCR test. So perhaps the mother's test came back positive. One of the other posts in the thread says the mother had PPRM (preterm premature rupture of membranes) at 25 weeks, and that's why she was admitted. If the mother did not test positive then the idea of testing the baby seems insane. Maybe more will be revealed as this story goes "viral".