OK...here is the confusion. You cannot have a 2000fps clip in FCP. What needs to be done is that clip needs to converted to 29.97...this making the image extreme slo-motion. Which is what you wanted anyway, right? The clip I have was of an explosion that was shot 2000fps, then converted to 29.97, thus giving me a gorgeous slow motion shot of this explosion.
What they need to do is convert this for you. I doubt that you'd be able to work with the original file.
Shane