S.B.
K. -
Go ahead and put the DVD on. What's the harm? If you are already a parent that's okay with a DVD in the car, then why would you stress about putting limitations on that? If it will get all of you someplace in good moods with no ragged nerves, then girl, do it!
It's a stage. He'll grow out of it. There is absolutely nothing you can do about it. (I think my son did this for about 3 or 4 months. I can't remember...)
But if you know that you've tried multiple solutions with no success, and the DVD solution works, why not just solve the problem that way? What's keeping you from allowing that to be the answer? That's what I would do.
Good luck! S.