If you try to jump while in the air it will buffer your input for .05 seconds and then jump as soon as you touch the ground. You need to hold the jump button down during this time. You can see it in the first video below.
While testing it today I discovered a bug when using it with slide. It's using a cached version of the slide speed instead of re-calculating it on the landing. This is how I was able to maintain my speed for my Tutorial record. You can see it causes me to jump backwards in the second video below.