Q: Mini Dvi to S-video/Composite/RCA

I have a 2007 black macbook and recently bought a Mini-DVI to video adapter (brand-dynex) and hooked it up to my older television (TV has no hdmi hookup or dvi, just S-Video and RCA) and I could faintly make out my computer screen but it was all "scratchy" and was moving across the screen. I changed the resolution and it became black and gray lines moving up and down the screen. I was wondering how can I hook my computer up to this older TV to watch movies online (I wont be upset with low quality). Do I need to purchase the Apple brand adapter or is there some "tweeking" I can do to make the Dynex one work? thanks