Parkour is all about keeping and adjusting your momentum. Once you gain speed be careful about your landings and steps. Try to make a smooth progressive flow in the replay. Try to avoid landing on completely extended legs or too far leaned back or forward. It's all about micromanagement. Also as mentioned earlier, just because you jump with your legs doesn't mean the rest of the body shouldn't move accordingly. Trying to recreate just a position for something is often not enough. You have to come into that position with the right momentum going etc.
It's as with most things, repetition makes better. If you need help with specific things in replays, feel free to post them in this board and you will be helped with.