The new SeaWorld fireworks show, Mystify, was scheduled to run through Labor Day, when park hours shorten again. No info yet on whether they intend to bring it back later in the year.
The fireworks show includes a "movie" story that is projected on two water walls. In order to see all of the visuals, you need to watch from the new Waterfront area. The night I went (a Friday in early August), it was crowded, but not unbearable. Your best bet is to look at the show schedule and get in place before the last Shamu show of the day lets out. You can get a good spot along the wall less than an hour beforehand, as long as you don't mind missing the Shamu night show.
I understand that on July 4, the crowding was so bad that many people who were there thought it was dangerous, since it's a fairly small area of the park that you have to cram into in order to see the whole show. I woudln't try it on a holiday if I was with someone confined to a wheelchair.
Hope this helps.
