While I'm sure many of you know this, there are hunters out there who are not aware that they can jump higher by holding 'Jump' button compared to just taping it. Unlike titans lift and warlocks glide, hunters jump does not teach you to hold 'Jump' intuitively as by just taping it provides rather significant height.
First 2 jumps were made by just taping jump twice while on the 3rd attempt each jump was extended by holding jump button.
Another video to better illustrate just tapping vs holding vs just tapping.
This is useful because you cannot reach some places like this https://www.youtube.com/watch?v=fT-4ERBAJ98 w/o holding jump button.
P.S. If you are still not convinced that holding increases jump height slightly simply stand near wall and test it your self. You'll see that if you hold each jump you reach quite higher compared to just tapping.
EDIT: One more video clearly showing difference that jump height is linear to the time you hold jump button: http://youtu.be/FpYMOuju3ZQ
Here you can see that extra height added to a 2nd jump as well. Works with the 3rd jump too.