I've been doing yoga at a local yoga joint for over half a year now. And while I'm not fat (I'm a skinny fucker), I didn't exercise much and had back and shoulder pains from sitting in front of a computer pretty much 90% of my waking hours. I can attest to how just regular yoga 2 a week can do wonders for your physique - and mental state. This looks even more focused. If I wasn't in yoga already I'd give it a shot.
And before I started I was told that I'd barely be able to walk I'd be so sore after my first yoga session - even though you never step off the mat. Tis true! Jesus, every muscle in my body ached! Now I can do most stretches without too much problem, though some still leave a burn the day after. I'm also not all that flexible yet, but it's getting there (I couldn't touch my toes with my fingers without bending the knee at first, now I can just brush them with the tips of my fingers).
Short story: Yoga is awesome, and if you can't or don't want to try yoga, then this looks great.