I think the analogy you used, speaks to the point he was trying to make.
If you run that same exact play 10 times, it will play out pretty much the same all 10 times. There is no in-game variations that happen. It plays out the same way because the Game Engine is Maxed Out and old.
Also, Speed only deals with how fast an animation is triggered as to give an illusion. In Instant Replay you will see that there is no variation in the running animations between the two, thus why we "Still" see gliding and sliding in the running animation.
Go back and look at some of those Mo-Cap animations and you'll see that barely half the movements in the Mo-Cap transition into in-game animations.
All because the the current Game Engine will not allow/can't handle the detailed movements.