I feel like we would've had a lot more information on Victoria if she's at the level of paranoid to require an entire hidden camera setup, I think that's a bit of a stretch.
If that was the case, I'm certain Kate would've dropped a few comments on how Victoria acts weird or paranoid, since the dev rarely outlines character behaviour without hints beforehand (i.e Fiona saying that Delilah is fucking nuts for example).
If we're going by that logic, it's more reasonable to think that Delilah saw something, went "oh shit she's a duplo, what do I do?" and texted someone she trusted, in that case being Victoria. That is if we're assuming Victoria is the blackmailer.
EDIT- I still feel like there's something missing for me to think that it's Victoria doing the blackmailing.