As a “published” (On Blogger.com) author, I will admit to this.
Often, when I watch either movies, or television, I find plot lines so “lame”, or stupid, that I re-write the story, as I would have presented it.
In my opinion, one does not NEED a degree, computer skills, or to read 1,000 books, per year, to be an author/writer.
All one needs is PASSION, about a topic/subject. If you feel a show, or movie, would be better, if presented, in a different way, and you write about this, then you ARE a writer.
I know this to be fact since I have written over 90 stories, myself. Most are my own creation, but a few have been about how differently I would have handled a plot line.
Remember what I was told when I asked Quora.com: How many stories must I write, to be considered an author?
The overwhelming answer was that: If you enjoy writing, then you are a writer. If you enjoy walking, then you are a walker.
Follow your heart, and soul. If it leads you to the written page, then enjoy the experience.
I find nothing more fulfilling, then knowing that (so far), I have over 100 readers, for my work. If my writing brings them joy, all the better.
All my best, for your writing SUCCESS!