Mate I've watched that clip about six times now and whatever that is in the corridor around the 2:14 mark is NOT a camera artefact, you can literally see it shift its weight like its deciding whether to move closer and that is exactly the kind of behavioural pattern I've documented with shadow figures here in Hampshire - they linger, they observe, they don't just drift through like a smear of darkness on a dodgy lens.
The shape is too defined for lens flare and too deliberate for a crew member, nobody walks like that.
Anyone else notice it seems taller near the end of the clip? Would love to know if the Waverly team caught anything on their thermal at the same time because that would basically seal it for me.