You may actually be better off without the natural light. The color is going to be different between the sunlight and the interior lights and will be much MUCH brighter. It will result in strong shadows and some weird white points.
If you are shooting video, shutter speed isn't really much of an issue since you'll want to have it set at your frame rate to get as much light as possible. Aperture you will want to set based on the desired depth of field for your shot, the wider the better to allow in more light and the ISO should be set to properly expose your image.
Options for dealing with the color mismatch between lights is to either gel the lights inside or gel the windows to alter the color of the sunlight. Alternately, it might be possible to use a large white reflector (even white sheets can work in a pinch) to try to reflect light from the windows back on to the subject from a different angle, but that can be tricky depending on the angle that light is coming in at.
The key is that you want to have a light source that fills in the shadows that is near, but slightly less powerful than the main light and you want them to be the same color. Your interior lights do not sound to be the right color or near bright enough to compete with the sun, so your options are really either shoot entirely with interior light or reflect the sun and shoot entirely based on light from the sun.
If doing entirely interior lights, (really in either case, but harder with sun only) a back light can also be helpful that is below and behind the subject to light up their outline and make them stand out more from the background. That's what gives the "pop" to the image. It is referred to as 3 point lighting (key - the main light, fill - the one that fills in shadows, and back - the one behind).
