How does Sin Cara jump into the ring over the top rope

A trampoline, much like the Spirit Squad used. It's not shown on television for, not only the shot, but also to make it seem he is inhumanly agile. Anybody who's been to a live event recently, or pays close attention to how the camera is placed so that the space just in front of the ring is blocked by people and it cuts where it would be visible, would tell you the same.