I don't know...I don't think .htacess applies to this situation. What I see is a heck of a lot of
JS programming.
Seriously, you've got to really know Javascript to do what I think you want to do. You'd have to use a thread to load the index page while your animation loads in the foreground. Two processes, a thread for each. I don't even know if Javascript supports that.
But come to think of it, you might need to do that in Flash. If your home page takes forever to load, I believe it's rather easy to tell Flash to play your movie in the foreground while the background loads.
Let me know if you get it working. I'll be very interested to find out if it works.