If you fall on your back, your speed is too fast for your body to keep up, hold still a bit for your body to lean forward and continue running.
If you fall on your face then your speed is too slow for your body, edit around 100 frames before the fall and lean your body a little less
Running/Tricking/Parkouring (and other creative things in TB) is about failing, realize your mistakes and try to fix them, friends. Even if the physic is changed, you can still do it if you know what you're doing.

One common mistake is that people will always do the same thing even when their run is starting to fail. They'll still alternate between contract and extend their hips and Pecs every 20 frames. This is wrong. Do not do this for the love of God. You have to learn to adapt to the situation. Literally every little joint - including your neck, wrists, and ankles - can impact the movement, stability, and overall quality of your run or whatever you are doing. Do not disregard them and try to experiment with different timings and combinations to incorporate into your run.

Please help, I Did all the first steps in the Youtube one with all the settings but my knee just slammed down and i fell D: please halp meeeee

Make sure you space twice contracting hips then twice extending. Also, on some mods it can have some problems.

Remember that you don't always need to directly follow up with the other foot. As in, you can extend the hip of the foot that you have forward, then follow up with the other foot. Be sure to use shift+ space for one frame at a time so that you can control the run easier.

My charcter keeps bouncing is that because of the friction?

My character keeps jumping up on the first step
-----
here is an example. to use this mod: folders,games,toribash,data,mods and drag this mod in

Um mocucha instead of showing how to roll why don't you do it so i can understand on how to roll anyways great job on doing this tutorial

You don't need. Do a straight run and try a roll, if you fail, reset the replay and start again right after the run, you will understand how it works time after time.

ya it rlly helped until I became a pro :>