Well anything you do with still photos that applies to video could be done if a suitable script were written, like taking 10 secs of video once per hour, shoot video on motion detect, stop shooting video when motion stops, monitor disk space to automatically work stop+restart record to work over max file size limit etc...
Scripts most definitely can't do any sort of video signal processing if that's what you're wishing for. I have no clue whether pause, refocus and zoom will work from scripts during video (those being three things CHDK may add to cameras that don't do them normally).