I watched the 4 min video.

Unfortunately Dr Berg seems not to consider the concept of biological half-time. I am sure he know the concept, just forgot to put it into his calculation formula.

He basically assumes that if his patient consumes 2000 IU vitamin D today, then tomorrow his patient has depleted all 2000 IU and has zero vitamin D in patient's blood.

This is obviously wrong.

That guy is a scientologist quack btw.

Here's one example of how incompetent he is: https://www.youtube.com/watch?v=JvKNzLRmzLg

He basically turns low quality listicle nutrition pointers into videos with a whiteboard.