If you enjoy this movie then you might also like this ebook:
The Playmakers". I haven't seen the movie but it sounds very similar, with Marlowe as the secret author.
I agree that the most likely author was Shakespeare, but it makes for a good story! Historical mysteries are always good fun and often written by authors who studied the period at university and have a lot of research material on hand - well, it's one way of making some money out of all that work!