3M makes a good one.

You can still see through at night.

Have used film in 3 of our 4 bathrooms. It has lasted really well, 15 + yrs now, with no issues. We have paned windows, and I only used on the bottom 4 of 6 panes. First floor powder room window is set higher, and is pretty well blocked by a taller evergreen in the foundation planting. The other 2 are second story. All 3 have windows facing the street or driveway. You can only see a vague blur of a person at night, and the film is really not at all noticeable in daylight. Film comes in different designs, so the design may make a difference… we used an all over small crinkle design. You can buy a roll - and also need a window film applicator (liquid) - at Lowe’s or Home Depot. If a pane window, first cut a template to fit from cardboard to use in cutting the film. If you have access to a paper cutter, cutting is even easier. These are NOT adhesive-type films. The applicator liquid makes it easy to slide into place - just remember to take off the film’s backing before applying.

If you are over 65 years of age, don't put anything on your windows, the neighbors will put it on their's.

You can still see through at night.

No you can't. I have it on my garage windows. There are different levels so you can get one where nothing shows through.