I tried doing the jump with the torch in Inkwater I watched this video: but I didn't manage to get to the other side... no matter what I did... Can someone give more details on how to do the jump? what to press and when?

Thanks!!

The first jump is a little awkward because if you walljump from too high up then Ori will bonk his head. What I do is jump into the wall from further away so that Ori dips a little before touching the wall, but it will take some trial and error regardless of your method. When you get a jump with good height, you want to begin torch hovering at the peak of your jump. This is as simple as just repeatedly tapping whatever your bind is for torch while holding up and left. If you get across with enough height then the final walljump up is not precise at all.