This is a fairly low-budget sci-fi movie which as far as I know is available only on Amazon. Set in the late '50s in a small town in New Mexico, it's presented as an episode of a television show modeled on The Twilight Zone, complete with an introduction in Rod Serling's voice and prose style. I found it enchanting, so much so that I watched it a second time. It's basically a straightforward UFO story, in many ways typical: it could be an episode of The X-Files without Mulder and Scully, but it's done with such skill and atmosphere that it gives new life to what have become the conventions of UFO mythology.
Hidden in plain sight in the title and in a few sentences spoken by one character is a twist on the nature of the visitors which distinguishes it from other specimens of the genre. I did not recognize the title, but its oddness--one would expect "vastness," not "vast"--caused me to search it out. Because searching for the phrase alone only returned references to the movies, I needed something else. Figuring it was a quotation, I added "Shakespeare," and there it was. (I was going to try Milton next if that didn't work.) It's from The Tempest. Prospero is cursing Caliban with troubled sleep:
Shall, for that vast of night that they may work,
All exercise on thee...
According to the notes in my Riverside Shakespeare, "urchins" are goblins in the shape of hedgehogs, and "vast" is to be understood as a noun meaning "void" or "waste." I'll leave further explanation of the twist for you to discover if you take my recommendation; if you don't, you won't care.
The main characters are two high-school students, one trying hard to be a fast-talking '50s-hip disc jockey, the other a studious girl who subscribes to Popular Science or something of its sort. And they're charming. If the trailer appeals to you, you'll probably like it, too.
I have to say that I was a little disappointed in the ending. But if you are going to end such a story, there are really only a few ways in which you can do it, and the journey to it is so rewarding that I can't complain very loudly.