While that's true "alien" doesn't necessarily imply "inconceivable". There are certain physical constants that are assumed to be the same no matter where in the Universe one is. This limits the possibilities from infinite to finite. There are also certain ways atoms of a given element can or can't bond to other atoms to form molecules. There are also ranges of pressure, temperature and radiation at which certain chemistry works and can be in one state of matter or another. Much of this was pointed out in the video.