I don’t recommend the first book. At least in my edition the typesetting is just odd, which makes it harder to read than it should be. The front matter indicates it was typeset in Mathematica, which probably explains it. The later books in the series don’t suffer from this problem.

The videos that it was essentially transcribed from are great tho.

If it exists, you could probably replace most of the first book with just a really good explanation of the Lagrangian, with lots of examples, I think.