That's one of the daftest PCNs I've ever seen.
Not only are there no stationary vehicles in sight, but the car doesn't actually seem to come to a complete stop in the box!
Other than that, the OP is totally bang to rights
@Ventz, although you are a driving instructor and sound admirably familiar with the Highway Code, it's important to understand that a box junction offence in law occurs (only) when "a person causes a vehicle to enter the box junction so that the vehicle has to stop within the box junction due to the presence of stationary vehicles".
Therefore, if the reason for the stop (even if there was one which the video suggests there likely wasn't) was for anything other than a stationary vehicle, there is no offence committed, end of conversation. On that front, the video evidence makes it abundantly clear you have no case to answer. There's no need to justify the stop in any way via references to hierarchy of road users, or duties of care.