This video is essential because it shows you the movement towards the net. Shots at the net must be return quickly because most of the time your opponent net shot is a shot for them to in order you to make a weak reply.
The faster or higher you can reply the net shot the better for you as you have more angle to return the net shot. If you get to the shuttle slow, pill you angle is less and you tend to reply a half court shot.
A net shot best return when the shuttle is closer to the net tape. The close it is to the net tape you reply the net shot, that shows how quickly you are towards the net shot.
Try this simple video out!