The answer is at the end of the video, and in the text below.
It has been a relatively mild winter in Massachusetts, but the blizzard of Feb 2013 put over two feet of snow on the ground, effectively eliminating most of the grassy and weedy habitat sparrows need. In such conditions the plowed edges of roads become an oasis of open ground and exposed seeds, and sparrows gravitate to those edges. Thus a Le Conte’s Sparrow, a very rare visitor to Massachusetts, was found in Concord on 12 Feb. I suspect it had been at this location, somewhere in the acres of weedy and marshy habitat, since at least December, and was only found because of the snow that forced it into the open.
Given its behavior, it’s no surprise that it wasn’t found sooner. Le Conte’s Sparrow is known for being secretive, just like Grasshopper Sparrow and other species in the genus Ammodramus. They rely on camouflage for protection and usually crouch when alarmed rather than flying. The behavior shown in this video – burrowing under matted grass – is something most sparrows simply never do.