OCD isn't just caused by watching a movie, there are a whole lot of other factors such as genes. Maybe the initial fear of watching the movie made a mark on your mind and interacted with your genes, causing you to develop OCD, or it might not even be OCD, only a professional can tell you that.
From what i know about unwanted re occuring thoughts, it's that they are usually the opposite of your character, but not always. For example someone might be a very nice calm placid person and in contrast, get thoughts of their family dead or them causing harm, and then do a compulsion to help relieve that.
A good way to cope with your thoughts, for now until (if you can) get some professional advice, is to do 'thought stopping'.
It's a simple technique but can be quite hard to master. Everytime you get a thought that you don't agree with and don't like such as that Samara is going to kill you if you don't count.
Pinch yourself, make yourself feel and believe that it's Ok and normal for you to have thoughts like these because you cant control your thoughts all the time. You need to make your mind realise that having these thoughts are Ok, and no different to nay others thoughts, and then your mind will have no reason to keep replaying them. Don't try and stop the thought happening, let it always play out in your head as far as it wants to go, and always remember it's ok.
If you want i can find a webpage which has this technique on it in better detail, it's useful for people suffering from OCD and people just having unwanted thoughts.
Did you know of OCD before you started experiancing these problems?
If anyone wants immediate advice don\'t hestitate to contact to me on AIM (AOL instant messenger) - aim: vodkasmodka
Eccentric! Not egocentric!