In the video, it's shown that there's a cone of galaxies and quasars that we have seen and mapped. What prevents us from mapping the dark areas? Is the the light from the other stars in the Milky Way?
I asked an astronomer and she said that the Sloan Digital Sky Survey (http://en.wikipedia.org/wiki/Sloan_Digital_Sky_Survey) really hasn’t mapped those areas (yet). No artifact, but really white spots on our map.
largely yes. that and dust (which obscures things), and also priorities - the kinds of surveys that provide data for these kinds of map are typically hoping to increase our knowledge of cosmology / large scale structure / galaxy evolution, which means that they avoid looking at the milky way because (for the reasons given) you're going to see more nearby "clutter".
Layman to layman: it's light that hasn't reached us yet. Light that left alpha centuri last week wont get into the cone of visibility for another 4 years. During the period of inflation after the big bang some parts of the universe got so far away so quickly the we will never see those parts.
I think you're confusing the boundary of the visible universe (the limit after which light cannot have reached us yet) and the unmapped volume the poster is talking about, which is inside this boundary. Alpha Centauri was emitting light just fine 4 years ago so of course it can be mapped.
