It is inevitable that one director (or scriptwriter) will borrow the story from another movie that they have watched before. They may not use the exact storyline but they will get bits and pieces of story.

If you do get a large chunk of the plots and storyline from another movie, are you suppose to give credit in the ending-credit? If so, how? (i.e. Story Based On "The Movie" by Director Name)

I doubt all movies are 100% original. Thanks for your time.

Lot's of people call plagiarism "borrowing"... doesn't make it legal. Your post is a bit unclear as to what you mean by "borrowing". If you mean "Inspired by" then often that is listed in the credits, but you must remember that you do not have the rights to borrow stories or movies that are not in the public domain.

It would be okay for instance, to write a whole new story based on a Shakespearean play, set in outer space, or feudal japan... "Inspired by King Leer" or "Inspired by MacBeth". No problems, the stories are in the public domain and most people would see the connection at some point anyway.

You have no right to "lift" ( more acurate than "borrow") pieces of a film and reshoot them unless you have the rights to the story OR you are doing a spoof, parody (Which establishes it's own, derivative rights, but that's another thread).

Sure, we are all influenced by the work of others. And no one owns the copyright to a plot line. It's easy to see a character, or effect, or a sequence and say "Ahh, in the style of Hitchcock, or The Matrix" again, that's just fine. But using whole pieces unchanged... No good.