What do you mean dangerous? Is it about the privacy policies that this project might violate? I think the concept is being used in securities agencies now but faceter is just making it public.
Like any technology, it has advantages and disadvantages. It's can prevent crime from occurring, gather evidence and saving records and give that a sense of security. On other hand, it's make privacy issue, I have heard about some employees that took legal action against their employers because of that.
Yes, they should make some posts or anything that will make the employees aware that the place is equipped with cctvs. This days, I am sure many of us now are aware that cctvs is all over the places.
Most of establishments now are already have cctvs installed. I am sure because of our technology now many people will be curious to try this project. I just hope devs are very serious to continue the development of faceter.