This one lost me the second George Lucas, a notoriously poor screenwriter, was used as an excellent example of a screenwriter who knows how to self-edit. There is some decent information here, but it's largely the same generic advice you will find in any book about writing. There is very little here that is specific to screenwriting.
It is also tediously representative, with the same point repeated multiple times over a chapter, sometime even with the same wording. There is also the small matter of the missing sentence. There are several that are cut off like someone accidentally deleted half while editing and wasn't paying enough attention to notice their mistake.
Overall, this isn't worth the read as there are much better options about screenwriting in particular and fiction writing in general out there.