Ref. No. 38 / 1144
In the name of Allah the most gracious the most Merciful
The answer to your question is as follows:
Cinemas and movie theaters are the center of evil acts. Hence it is not allowed to work there and cooperate on unlawful activities. So working there as a watchman is also not permissible.
And Allah knows best
Darul Uloom Waqf Deoband