The initial scrolling text behaves erratically. First the last line of the first paragraph ("Forgotten Realms...") will jump sideways to the right to line up with the line above, and then back to the right again. Then the initial N will jump down, then back up while the rest of the text scrolls off. Then, as most of the text has scroll offscreen, all of it will jump back down again.
I have just begun BG1 with GemRB, so I don't know yet if these kinds of problems apply to all scrolling narration text.
GemRB compiled from Git repository source July 19th, 2012. GUI enhancements off.
Mac OS X 10.7.4