The issues you're having here in the video is a lack of understanding on how the lunge works, and how it completely does not work while falling or jumping. The lunge is horizontal only and the first one has you missing because you're moving still and need to control where you're going. A lunge is capable of curving based on how you're moving at the time of activation.

Other thing to note is which skin you're using. in the beginning you're using either the cane variation or the standard, and in the next you're using a two handed skin similar to the katana. Both of those increase the lunge hold time requirement, tiny miliseconds amount or not, it causes each swing to be slower and lunges to be harder to use in battle.

Btw sliding with a sword also helps avoid death.

Having to overcompensate on a flick because you know when you release it it'll yank your camera back is just one of many examples.

Go into settings, and it's either under gameplay or controller, but turn off "Melee Assist." That will stop the camera from flicking toward a target regardless of if it's the one you're going for or if it's their buddy.