It's in the title and on the first post: he's specifically asking about filming a fun fair at night...
I disagree with this statement. Because of the "performance constraints of the imaging system", as you just called them, the settings you use on a bright day are completely different than what you use at night. On a sunny day, you have options. Shooting in low-light or at night is always a compromise, even with a DSLR equipped with much faster/better lenses.
For still photos, we agreed that the best combination is to keep the ISO low, and go for longer shutters. That's not much of a surprise, if you are into photography, but it's good to know it holds true even on the P3S, which is not a tripod.
For videos, I'd like to understand what's the best compromise...