I was the programmer responsible for SR3 and 4's cinematic system and I will try to be of help. When I get in tomorrow I will try to compile some information on how our cinematics are handled. For the most part the pipeline for SR2, SR3, and SR4 cutscenes are the same, though there are some differences. If you have any specific questions, let me know and I will try to answer. As a long time PC gamer, I am excited at the possibilities that mods will bring.