That it is my first post doesn't seem relevant to me, but hey, if you want to carp at that, I don't care.
And then back to your question.
In your question you are assuming that the axis of the earth stands at 90 degrees of the circular orbit it makes. This is wrong, the axis stands at an angle of (I don't know the exact number but it's around) 23 degrees. This makes that in the summer days are longer then in the winter. But not everywhere on the north and the south pole you have a half year of darkness.
This is kind of what's said in the video but hey, if you want to read in stead of look, I still don't care.