As I said on another thread, according to the DM it was regular CCTV footage leaked by an anti-lockdown member of Hancock's staff. He thought Hancock had been too eager to lockdown, so leaked it.
The original reach-out to the media, according to the article, came with this memo: "I have some very damning CCTV footage of someone that has been recently classed as completely fucking hopeless."
From the pictures they've used, it looks like there was very clearly a camera on the ceiling, adjacent to the smoke detector. I imagine that if you're around those black-domed ceiling cameras all the time, you sort of forget that they're there.
You can tell the layout in part through the absolutely (though unintentionally?) hilarious graphic they've created for the article: it includes things like "white board," "Queen painting," and "KISS DOOR" (all in capital letters).
It's a DM article, so make of it what you will.