I think one point of difficulty is that the video makes it seem like the dot product by itself give a useful cosine based result but you need to divide the dot product by the product of magnitudes to get a useful cosine value. Otherwise (1,1) and (1,0) will give you the same cross product value of 1 when compared with (1,0) which is obviously not helpful.
Thank you for your suggestion. We really appreciate this and take this into account if we create other courses or re-do this one.
Kind regards, Lisa