XZ-1 underwater videos
I think the quality looks about right for XZ-1. In other words, its video sucks. At some point, I even feel like get my "HD" video converted to 480p because they don't really qualify as HD.
When you zoomed in, the video tends to go out of focus. I am not sure how manual focus works with zoom. I suppose the camera tries to compensate the focal length change. I would stick to F4.5 or smaller if needed.