I've read a post about this before, but I'll share my experiences. I have taken my camcorder inside rides and shows. I've taped:
Small World, Peter Pan, Snow White, Haunted Mansion, Pooh ride, Voyage of the Little Mermaid, Hunchback of Notre Dame, Great Movie Ride, Safari ride at AK, etc. My husband even taped Star Tours- talk about a bad video- makes you sea sick to watch!
I think most places allow video.
As far as night, I advise practicing before you go. Different cameras perform differently. For instance, my camcorder taped Spectromagic just fine without using any special effects. My SIL's didn't the first night and the second she used Nightvision- which really distrots the colors. Try using you camera at night before you go with different effects.