Ok, i am going to say this again slowly. A light, for many reasons as you have stated, can grow in size as it appears to the eye. HOWEVER, it cannot grow and at the same time intensify. As the light grows it will also disipate in intensity if using your logic. What you see on the videos is not car lights. If you see what is in the videos in person then you will have the knowledge you need to comment further on this. If you do not see exactly what is in the videos then keep going until you do.
At the moment I can think of several physical models that would allow a distant light source to appear to grow in size and intensity. I can fathom a light source of curious origins but have a more difficult time understanding why people find the need to lie and deceive to make themselves feel important.
It would have been sufficient to state that it "seems implausible" or "I believe", but to state unequivocally that it "cannot" is to deceive the reader that you possess a scientific knowledge of the physical properties of light. That there are allowable circumstances, that may or may not be the case here, makes your implication a complete falsehood. At the least, try to be honest.