there are some things that help to know when making replays,
In order of importance:
1.Save every time you get another part of the replay finished (ex. i make a cool opener that i like, but nothing breaks.....save it, than i make something break, save it...ect.)
2. If it doesnt work the first time than go back with r and move some things around till it works.
3. Momentum, you want as much of it as you can get...so dont move things around alot...
4. When you go for a punch or a kick, if you move both arms together instead of one forwards and one backwards, you get more speed/momentum.
5. This is what you did wrong in the replay. You "can" break a person withought hitting a joint (ball) but its tough, and you need alot of speed, so usually people aim for the joints.