In the video, when you look at about minute 25:20 and further, you see a very strong jerking, like a slide show. This is maybe because he was driving too fast for the game engine to load all the stuff in a timely manner? I never had this jerkiness during my playthough. Maybe a little bit here and there, but not that long in any way. However, I just can't imagine what he is trying to prove.
must be the recording program. you can see, that the ms and fps are stable. so its defintely not the game (engine). Or his hard drive he is recording on, is the same the game runs on. Only things that i could imagine happening here