If you don't get a window table you can always just tell your waitress you'll be going out to the balcony just outside the restaurant to see them. That is a great view and since the balcony is lower than the window, you can stand there and not be blocking anyone inside the restaurant. I saw several people get up and leave and go out and watch them when we ate there last year. What I might suggest is that you make an ADR for more around 7:30 if you can change it. That should give you enough time to finish your meal if you don't get a window table. If you do, then you are all set!
And we had a decent view from our table that was the next area away from the window. They pipe the music in which is nice.
We love Tokyo Dining, its become one of our favorite restaurants for food and the experience.