Cinema in the context of a porn video tag refers to scenes that are shot in a movie theater or cinematic setting. This can include various scenarios, such as:
1. A couple having sex in an empty movie theater during a screening.
2. A scene set in a cinema lobby with people watching movies, while the actors engage in sexual activities.
3. Characters watching adult films together and engaging in sexual acts.
4. A scenario where a character is working at a movie theater or projection room and has sex either on duty or during breaks.
Cinema as a tag usually denotes scenes involving erotic roleplay that takes place within the context of a movie theater or related environment.