How to reveal and hide my preloader......additional effect that will look good!

Is it possible to use a movie as a mask.

The reason I ask is that I would like a large rectangle “gray” to reveal all my preloader graphics, then as the shape tween completes for the preloader to begin.

And when the prelaoder reaches 100%, for the shape tween mask to hide all the preloader content and reveal the main design template.

With the preloader being based on three keyframes, or more like two key frames, I am unsure if this is possible?

If it is a possibility Then please provide me with any solutions in going about this successfully for my project.

I hope you can help or point me in the right direction for this thread.

cheers

Trevor Saint