Is there any prohibition in having surveillance cameras operating on Shabbos? If not, why is is any different to filming a Bar-Mitzva, etc?
While some (including R' Vosner) are stringent. it is generally understood that to operate such cameras as well as walk past them is perfectly permitted. The difference between surveillance cameras and filming a function is that when filming for security purposes, you don't actually want anyone (other than intruders) to be filmed.
Hence, it is considered a 'pesik reisha delo nicha lei' etc.