The park itself is only open normally to 8pm. Are you talking CityWalk? Which will be open past midnight.
"And yes, we implore EVERYBODY to follow the park rules. Having off-ride footage is great, but any still photo's or video's taken ON the coasters at SFMM are strictly against the rules. They are there for your (and everybody's) safety." "Six Flags doesn't allow ANY loose articles on their coasters, and they don't allow video taping on their coasters. " BUT, " This is not true. Six Flags does not allow ANY On-Ride video or pictures on the rides. The ONLY way is if you get explicit permission from Park Management." ???
Park usally closes around 6-7PM on New years eve to start getting people into the Waterworld Stage for the Fireworks. There are also I believe live events
happening all around the Citywalk/hub area and then right before Midnight, they countdown to the new year. Its usally crowded in the night in there so if you go into the park that day, do it early and then once you get done probably 2 hours before the park closes, Get something at citywalk for food and wait for them to get you into the Waterworld stage but there might
be a line already for that.