Learning how to properly pop off the wake and using a tantrum as an example is sort of a conflicting in concept/idea. Like Tom said, that tantrum is a trip edge trick, your getting your "pop" or lift off the wake on a tantrum is not as much from the wake but more from the fact that you are tripping the board. Tripping, again to echo Tom, is a edge change at the top of the wake, literally going from your heels to your toes. Now you can use the added pop of the wake to your advantage in that the higher up the wake you trip your edge the more upward pop you will get. The same style trip is used on toeside front rolls or scarecrows. A good way to learn to trip to board correctly is practice learning the air trick (no wake behind the boat) edge change. Watch a video of Murray doing belaires or tweety birds and watch how he is doing air trick by just aggressively changing edges. Anyway a video would be great here just to see on a regular straight air how your are edging at the wake and how you are leaving the wake. For the most part if you are not edging in properly with the correct body position, popping off the wake is a moot point.
this is an oldy but a goody. Around 2:05 mark