The Game footage was edited slightly differently than the movie and it had some alternate takes.
For example, it had Dooku saying "Just because there are two of you, do not assume you have the advantage" just before the duel started.
It also had slightly different dialogue in the scene where Obi-Wan and Anakin chat before he boards the cruiser and heads to Utapau.
Also, of course, it had the softer Papaltine voice telling Anakin to leave Obi-Wan's body behind instead of the re-dubbed version.
What else? Also, R2 made a sort of sympahy wimper when Grevious told Obi-Wan that it wasn't much of a rescue.
I think everything else was just edited tightly, excluding parts that did end up in the film.