4.3 Cut scenes
In addition to the use of video the games can opt to do things in engine with text, 3d and 2d all being employed to various ends. This has two benefits to hackers as it is small, quite easily understood and quite easily manipulated compared to plain video where replacing existing content is tricky at the best of times (if you do have to edit video again consider instead that it all ends up in the 2d engine and inject stuff there outside even the video handling code).
How you actually end up hacking it has elements of 2d imagery in OAM handling (basic OAM animation was already covered), 3d manipulation including distortion (you can move bones but you can also move vertices) and aspects of level design where you have to figure out the format controlling the movements which will be covered next.