While going through a series of yoga postures is not particularly effective in calorie burning (compared to more vigorous cardio workouts) or strength building (even yoga sites suggest incorporating some [non-yoga] strength-training to build & maintain muscles), what it does well is help the mind focus and concentrate... on holding postures, on clearing the mind, and especially on maintaining the regularity of your breath.
Ok, you might think "Big whoop, I'm aware of my breathing. How does that help me lose weight?" But by building an awareness to something as basic & involuntary as your inhales and exhales, it also helps build consciousness for other seemingly-automatic behaviors, such what you're putting on your plate at the buffet, or rather to dip into that snack dish at the conference room, or couch potatoing the hours away instead of doing something more active.
As an added bonus, what's particularly recommendable about this one is that it's adapted to multiple levels of fitness and flexibility, from a beginning, fully-modified workout for stiffer, less flexible bodies to an advanced, unmodified routine for more limber folks who's used to doing yoga. You can even see all 4 types of modifications at once so you can determine which is best suited for you, as well as exercise together with a friend or a partner of a different flexibility level.
Plus, the whole routine is very soothing with Ms. Deason's gentle voiceover (much more appropriate than having her talk about her postures & movements while she's doing them,) peaceful background music and a serene desert setting -- unlike some yoga DVDs that try to power fast-track you through poses, self-defeating the mind-body connection by inducing, rather than relieving, stress and detracting from the focus on breath, body and posture.
The result, a workout that's both relaxing and engaging, pushing both the body and mind throughout the routine, as well as a nudge to make better lifestyle choices throughout the day. So give this DVD a check-out, and even if you find it's not for you, hopefully you can incorporate some form of exercise that helps align the mind with the body towards the common goal of better health & better life. That's certainly something I can say Namaste to.