This level doesn't require any moving left or right. All it requires is jumping. Just jump onto the platforms, being careful not to fall into the void where there are gaps.
When you start the level, don't do anything. After you fall, you will land on a previously hidden platform below the previous one. Then, jump to the underside of the level (change gravity). Go straight until you get the bonus, then jump again to complete the level. Just be careful not to fall down the small pit right before the end of the level!