Hmm... now this gives me an idea:
We could have script commands to read and write any value in CHDK config. Much like get_prop/set_prop but for the raw chdk.cfg values. I don't mean that these commands should be a preferred way for any task (just like get_prop/set_prop aren't), but they would provide a way to do things like this video quality experimentation before they are implemented properly (some things may even be better left unimplemented, but it may still be good to have access to them for testing).