How do I the floor keep the same Y axis?

How can I do to the floor of my game keep the same Y axis when character jumps, just like in Super Mario World?

The ground Y axis changes only when Mario goes up or falls on the screen.

Can anyone help me please?

See the video at 5 minutes to see what I said: youtube.com/watch

(Sorry for my bad english)

I think this may be done by having a sprite span the entire middle of the stage, and when player touches it, then apply the "scrollto" function