I have download some movies , and can't play them. Someone suggested a video converter or player. It says you need Windows or MAC.
I am a gadget novice and don't really no what I'm doing. Also the brightness on my screen keeps coming and going, I have it set on auto.. please help...

I am a gadget novice and don't really no what I'm doing. Also the brightness on my screen keeps coming and going, I have it set on auto.. please help...