I'm not sure how well that would work...
A simple on-screen action may take two or three lines in the script. It would take you longer to read it than it would for it the play out in the film. Sure, you can read dialogue quicker than it may be spoken (hence the reason the 'one-minute-per-page' rule works out), but you'd constantly be playing catch-up.
Also, as I'm sure you are fully aware (and I suspect is part of the reason you would like such an app), movies change constantly, from script, to production, to the edit. Chances are, the script won't tie up with the film at all... especially when you're talking about Tarantino... even more so with Kill Bill (which, I believe, was written as one movie, then split up in the final hours!).
Your best bet might be to print the script (or just load it on to a mobile device) so you can read it at your own pace, pausing the movie and flipping to the correct page whenever necessary.