i downloaded 2 movies and it will only let me watch the 1 min preview. can anyone help?

i downloaded 2 movies and they are both rar files and they will only let me watch the 1 minute preview.. does anyone know how to ix this or if theres a way to convert it to a different type of file.. both are zipped as well and when i try to extract them it does nothing.. plz help me lol

What exactly are you using to open the rar file? How did you open the rar file? What did you get when you extracted the contents? What file type was it? What did you use to open what you got?
We need a lot more information...