Does anyone have any sources for what the halacha is of running a home security CCTV system with the monitor on over Shabbos in a place where it is easily visible within the house? I'm specifically interested if anyone discusses the problem of having benefit over Shabbos from being picked up on the camera - eg. for someone to open the door for you.
The Star-K have got a pretty definitive rundown here with sources.
It discusses whether or not pictures captured on a monitor come under the banner of the melocho of Kesiva - writing, and provides 5 reasons why it would not be kesiva mideoraisa.
After a great deal of discussion - see there for more, the concluding paragraph reads:
Ideally, a Jew should not leave a video camera on during Shabbos. If it is necessary to leave it on for security reasons, Rav Heinemann paskens that he should turn off the monitor and make sure that no noticeable changes occur during Shabbos. If no change that can be detected by the five human senses occurs, it is not considered a melacha on Shabbos. However, it is not sufficient to merely cover the monitor, or conceal any noticeable change in a similar fashion.