What is the best way to work on your abs

I am 19 and only weigh 145 lbs. I'm not fat, but I do hold a little bit of a belly. I have 2 abs videos:

8 Minute Abs

Power 90 Workout (Ab Ripper 100)

Whats the best way to work on my chubbiness in my belly? If I run around and play basketball while sweating a lot, how do I know if I'm not just losing body fat in my legs?

How can I get the fastest Results? Please let me know how some of you did it.

I appreciate your time

My AB Workout consists of 3 basic exercises. These exercises work on the 3 abdominal groups, worked out in the correct order to get maximum results.

1. Leg raises (Rectus Abdominis)

2. Side Crunches ( External/Internal Obliques)

3. Straight Crunches (Transverse Abdominis)

Here is how it works. You want to get up to where you are doing 3 sets of 25 reps for each exercise. But start with one set of 15, then 20, then 25. Then start with 2 sets of each, then finally 3 sets. Only allowing a 30 to 45 second break between sets.

1. Lie flat on a mat, with your hands placed at your lower back, close to your butt. Now with your legs bent slightly, and toes pointed away from your body, with legs together, lift your legs up 6 inches off the ground. Each rep consists of lifting your legs from 6 inches to 12 inches. You cannot put your legs on the ground till the set is done. Go between 6 inches, to 12 inches, and back. Each time you reach the 6 inch mark, count one rep. Each movement should be one second. One second up, one second down.