For kicks on my lunch break, I watched 30 seconds of the first video.
I'm assuming the video is something about why it isn't dark at noon after 1/2 year, which is explained by the difference between sidereal and solar days which are (for simplicity) ~4 minutes apart. Because ~4 minutes multiplied by (for simplicity) ~180 days = 12 hours, there's your explanation.
Next.
So why after 6 months you will be looking in the opposite direction at night but still see the same stars?
Some stars you see will be the same, but some won't, and how many stars are the same depends upon where you are. The earth revolves around the sun and rotates on its (tilted) axis with a slight wobble. The earth isn't spinning on multiple axes, so some parts of the sky will always remain visible at night, particularly if you're closer to the poles. At the poles, the night sky won't change much at all from season to season. Generally speaking, as you move farther away from the poles, the more variation there will be from season to season.