For starters, I don't know how good of video is possible with the sx50. It's a compact camera, so there will be limits.
As to the noise and/or fuzziness. Depends on if it's noise, or fuzziness, but I suspect both would be caused by the same thing - lack of light. Photography/videography takes a surprising amount of light. When you're indoors you need a surprising amount of bright lights for good picture. I'm not sure what you mean by 75 volts, but a 75 watt light isn't bright at all, not for a camera. How does the video look if you shoot outdoor?
If a camera doesn't get enough light it's going to do three things - open up the aperture, raise the ISO, and increase the shutter speed. Raising ISO adds noise, plain and simple. Opening the aperture can reduce the amount of the photo that will be in focus, making things look fuzzy. And increasing the shutter speed can allow movement to show, also making things fuzzy. Without seeing your video it's hard to speculate which it is.
