I have always been curious about this process. Do officers record video in the event that they or other immigration officials need to scrutinise the details from interviews, whether on the part of the officer OR the passenger, later on?
There is no evidence to suggest that immigration interviews are recorded. If people were being recorded it would be on the privacy notice:
For immigration purposes,Border Force Officers do not tape or video record interviews at the desk or in their interview rooms. The interviews are supposed to be hand-written verbatim (both questions and answers). If an interpreter is used (speaker phone) the notes will be in English.
CCTV in ports/airports in the UK are the port/airport operator's property but are made available to Border Force & Police to (for example) track an individual back to a flight if they arrive at the desk with no passport and claim asylum. The airline can then be identified and and the passenger's point of departure prior to the UK can be ascertained.