I noticed that it was already called "Entertainment and Movie Talk", thus covering all those besides movies under entertainment.
"Discuss anything relating to the entertainment industry such as movie trailers and reviews, tv shows, video game, or celebrity news."
I see that you have mentioned trailers and reviews specifically. Just like the description for Props and Costumes, I think the following could also work.
"Discuss anything relating to the entertainment industry such as movies, tv shows, comic books, video games, music and celebrity talk."
Good choice going with the title "Conventions and Prop Parties".