Can I get some closure on this 2012 doomsday thing

You want closure, but you haven't bothered to do any real research.
Youtube is NOT a reliable source of science data.

Even if a planet could only be seen in the southern hemisphere, you do realize that there are astronomers with some of the best telescopes in the world in the southern hemisphere. Why haven't they found it yet?
Nibiru doesn't exist.

People can say anything they want - where is the proof of these underground bunkers?

Try here for some facts:
http://www.2012hoax.org/start

The chances of 2012 doomsday are zero to none,

Everything people are spewing out is simply conspiracy theory, and most likely used to over exaggerate a typical day, the Myan calendar works in cycles like our own, it restarts approx, every 7000 years, which happens to fall on the 21, it does not mean the world is going to end.

Think of it like this, our calendar ends on the 31 of December, it doesn't mean we are all going to die every December 31st.

(1) Things like planet move through space at about 50,000 MPH. In order for Nibiru to HIT US on December 21, 2012, it could be NO MORE than 5,000,000 miles away from us RIGHT NOW! That is "only" about 20 times the distance from the earth to the moon!

IF Nibiru was that close:
(A) WE COULD SEE IT!!!! It would appear bigger than the moon!
(B) Nibiru's gravity would have already ripped the moon out of orbit, and probably crashed it into Nibiru thus breaking it into a "storm" of rocky bits!
(C) The tidal forces of all that "gravel" where Nebr used to be would ALREADY have upset earth's orbit, tides, and would probably be causing some MAJOR earthquakes all over the world. California would probably already have fallen into the ocean, the Himalaya Mountains would be just small hills, Japan would be GONE, and Tehran, Iran would be totally flattened!