Do you need a whole forum. Does the fact a forum called chitchat exist and it isnt explicitly called POST MOVIES AND MUSIC HERE you cant post your movie and music threads in Chitchat. Is it some magic barrier that stops you from doing so. It isnt against the rules to post those in Chitchat is it.
Just do what I do and put like [Trailer] or [Movie] at the start of the thread title and use CC. No specific need for a entertainment forum when theres only 30 active members and the front page of CC lasts for like a week.