Try not to worry so much. The object is reputed to be commensurate in size to jupiter or saturn and if that were the case, the planet would be visible based on the purported timetable so imminent, eg. 2012. Jupiter and Saturn are visible in the sky. On a good night you can find them yourself with a telescope. Even if the planet were to be hiding behind the sun for instance, there is no evidence to support the notion that should that object pass close enough to us, it would affect the core of the Earth to the point to reverse the poles.
In reference to pole shift, it has been proven that this has happened within the history of the Earth before. In fact, our ancestors probably dealt with this issue before and our species is still here. In fact, scientist's believe that the waning of the magnetic fields is the entering of the Earth into the gradual transition of pole shift. This may affect climate but not to the point of elimating most of mankind.
And lastly, the planet X nibiru idea derived from a lady that supposedly had a psychic connection with an extra-terrestrial.
Lastly, the video references a mssing planet in the asteriod belt just after Mars and before Jupiter. There is scientic justification to conclude that there used to be a planet in that gap based on the overall formula deduced by scientists that in essence states based on the masses of the planets, their distances, and the gravity associated with the sun as well as the masses of the planets, there is a natural formulation for each planet from the sun and the distances between planet to planet. The only area that this formula fails is that gap between Mars and Jupiter. The formula would dictate that there should be a planet there as well. However, as we all know there is not. It is called the Titius–Bode law. However, this too is not without problems as it did not do a good job of explaining the orbit of Neptune. But because this is after the Mars-Jupiter connection we should at least consider it to have as much merit as some doomsday video on a planet that is either supposed to strike us or screw with our magnetic fields.
In other words, try not to worry yourself. By the way, if I missed anything in the video or if I got a fact wrong from the video pleade let me know since I scanned it and could not read all of the descriptions because of the font and limitations of my eyesight.