Perhaps voter could feel intimidated as been recorded.As a measure of transparency, for example in Mexico we use a 100% plastic transparent ballot boxes, so you bear out if it is empty before starting voting process and what voters put inside.There were strict rules about where they were to be placed and what they were permitted to watch.There were reports that some, especially rural, voters were intimidated, believing that their actual voting was being observed.Was more disciplined a process than dozens of party observers crowding around the tables and screaming at each other over disputed ballots.Locally built system, implemented by the election authority, with support from USAid.In fact, infraestructure of some places used as polling sites do not allow to put them.
In our case, the idea of introducing cameras seemed to be a vendor-driven malfesance: no competitive tender was conducted, and more than USD 100 mln were spent for the equipment that was used only once without any remarkable use; - As mentioned by the previous contributors, the secrecy of vote should be respected while setting the cameras at the polling stations; - One should be aware of the limited character of the information that the cameras can provide.
They can demonstrate some "well-visualized" violations (like massive throwing-in of ballot papers), but not manipulations in the voter lists.
Also, vote counting and tabulation, in most cases remained because these processes took place not in the area observed via the cameras or the quality of the video wasn't high enough. Albania actually used a system of cameras mounted over ballot counting tables to increase transparency and remote-monitor counting in 2009.
What countries use or have used video cameras/webcams in polling stations as a confidence-building and transparency measure?
How have these countries assessed their experience, taking into account costs and the effect on public confidence?