Your body is leaning a lot, wich make your weight in front of your tori and make the balance harder. Try to raise a bit your body by extending a bit more your hips. That will allow you to make smaller steps, to get a better contact on the ground. Then, you may notice that your feet falls on the heels, wich is because you are extending your knees too soon, i suggest you to extend your hips a bit sooner, wich it will make your body raising a bit (and make the balance easier) and make your feet fall flat on the ground. Use your pecs like IRL, that will help you too. For example, if you are contracting the left hip, contract the right pec. when you contract a pec, you can just let the other relaxed most of time.
To get a smoother run, all is in the relax mode. Use relax at the maximum. Initiate a move by contracting/extending and then relax it. For example, when you are raising one of your foot from the ground, contract the hip 10/20 frames, then relax it 10/20 frames then extend it to make the step.

That is really well done for a first day trying at it, running - and parkouring - is one of the hardest thing to do in toribash, don't give up