Thats not to say you shouldn't strengthen your core - thats a good idea for injury prevention, general fitness, etc, but getting a stronger core will not give you a six pack.
I would say that injury prevention is the number one goal when doing physical activity. Warming up might not look cool and sexy either, but it's essential. Not to mention the fact that a strong core will pay off exponentially if you do basically anything aside form core work. Athletics, weight lifting, sports, gymnastics, shit even physical labor of any kind.
Flow is right though, it is advanced. I couldn't do the whole thing when I first started (probably can't now either yet). Depends on your level of fitness, but you do have to be doing a sport of some kind actively, preferably while also lifting weights. If not, find workouts that emphasize using your legs instead of your upper body, and also exercises that are dynamic (twisting your spine, varying motions).