After watching this video and trying to figure out how they're doing that Save/Load thing, I finally figured it out. Had to do a lot of research but there is a script you need to put into the ini file that'll let you save/load at any point in the game, including cutscenes. I was able to replicate this run quite well. However, I'm still not sure how he's doing a grenade throw that seems to throw farther than normal.