I think the result of the work show in this tutorial is really bad. I don't think anybody would buy that this have been shot at night. If people understand that I was the idea because to me it looks nothing like night time.
My first advice if you want footage that look like night time, is to shoot at night time. Your image may be grainy but that's what looking in the dark is, even our eyes gives grain at night.
If you have to choose between bad but realistic image and clean but unrealistic one, please always go for realistic. Good image don't make a story.
Then if you really have to make a day for night, first go outside at night and see how it looks, then try to mach it. For me the first important thing is that without any source of light we see nothing. So if I want my day for night look realistic (and still see something in it) I ad sources of light, make the window of the house brighter and yellow, etc.
In my opinion the time and effort it takes to make a day for night look realistic is so big that for independent small production I would just buy a few led light and shoot at night.