Yes, the cameras are functional. I do not believe that someone is monitoring them at all times but they are taping. The reason I know for sure is that my wife claimed that the dealer had made a mistake on a fairly large wager and they said that they would review the tape. After several minutes they agreed that the tape verified the mistake and she was paid.
It was an honest mistake and the tape worked in her favor.
BTW, those video cameras are mostly to watch the employees in Vegas. On a cruise ship it would be hard for an employee to cash in the chips.