Sorry to be direct, but you are wrong, first you do not reduce noise or grain with filters, and second, higher frames do not create a sharper image, this is higher shutter speed that creates sharper images, and lower shutter speed that create motion blur. You are confusing shutter speed and frame rate here.ND filters will help to soften an image, Using a slower frame rate allows more image in and creates a natural motion blur (more natural to the eye). Higher frame rates create a sharper image (good for slow mo or stop frame). But a very hard image. Remember 4K has alot of information to process. It's a point of diminishing return. I think the P3P cam. is really good for the money.
What I see in the Op's video is not noise but poor quality, maybe due to an optical problem on the camera, or wrong settings at import or export.