Just 'cause I've been having fun coining this term...
I usually fly around 9"-12" out on the top leaders, depending on the amount of stretch in my top lines.
What allows me to "whump" the kite is having the sail relatively flat to me on it's base setting. When I "whump", I hit all four lines and it loads the sail - flexing (curving) the leading edge, which in turn flares out the trailing edge...
More obvious examples of the kite doing this are at (exact times, may want to start 5 seconds before):
0:53 - soft/medium impact, more subtle application, initiating into a straight line on the ground pass
3:08 - hard impact, again initiating forward flight mid-window, away from the camera
3:10 - " different angle, you can really see the sudden flex and speed
(generally appears as an impact into the center of the kite, followed by authoritative movement)
Once the kite is whumped and in motion, speed + wind sustains that pressure like a siphon. as long as you're on all four lines.
Stop and the pressure slides out (kite flattens), tap it again (kite curves under tension) and you're off.
Same effect as using less brake (shorter top lines), with more power on demand and less over sheeting.
I'm using the same technique nearly all the time through many movements, but it's applied at length, grading power in and out to stay "at the end of the lines" in terms of tension.
Over-sheeting (drives me crazy) in short, is when a pilot unconsciously releases the trailing edge (bottom lines) too much and pressure slips out the back of the kite, requiring larger inputs on your brake lines (speed, turning), over sheeting is easily identified by a distinct fluttering noise from the trailing edge... It's also visible at times in the center of the kite, around the logo, where you can see there's no pressure, it goes wrinkled or flat in full forward flight, instead of being fully curved from pressure.
With more power (whump/load) and "brake", my controls are more sensitive (allows smaller inputs for same affect), smaller inputs equal less variable and easier accuracy, but I also have to be a little more dynamic physically. Totally a style thing, there is no right way to fly a kite (other than safely), but you got me excited and I had to get it out of my system - feel free to tear it apart.
More KiteLife discussion on "whumping" and tuning here, including a photo of my favorite handles and leaders.
Best advice I can give - taste it all (if only for a few minutes), borrow, morph and invent your own flavor.
Most useful thing I ever did for my skills - (1) fly every possible kite variation (2) in as many different conditions as possible (3) as much as possible.
Boy, am I whumped - sorry for the ramble!