I speak a bit about it throughout the video and wrap up at the end.
Heres what I think would be the most effective changes
* Change the controls so that you can move mid air rather than be stuck with your movement from starting the jump.
* Have the camera in levels movable like it is in the hub world. Sometimes you can't see where your going.
* Add some checkpoints in the levels, it gets tiring to redo the easy part at the start of the level over and over.
Hope this helps :)