Ugh. This was already Founded by TiMe4FiGht like. months ago,but he deleted the video. So Thx for remindin it back
This is actually called "Pushing". You push your teamate over this "invisible barrier". It takes a while, but it will be done.
Another way on how to do this, from what I found Thx to Time4Fight is, someone crouching under a another person and u drop and move around, and he jumps on you again, well to difficult to explain.But yea w/e