At night with the inside of house lighted. What kind of privacy will this film offer from lookers outside looking inside?

As with all one-way vision materials, the visibility is dependent on light ratio. During the day, when it is brighter outside, you will be able to see out while not being able to look in. At night, this reverses. If the lights are on while it is dark out, you will be able to see in, while not being able to see out.