Yoga is intense. If you are like me, some of the moves won't be possible at this point. Over time I can definitely see this helping flexibility and overall muscle growth. Hell, some people do Yoga only at a gym and get into really good shape. 1.5 hours is long, but whatever Tony says I do.
Also, you are right about the 6 months thing. You might see results, but they won't be anything you were expecting. This workout wasn't made for people who want to take their sweet time to get into shape. The whole point of muscle confusion is so you can continue to workout without a plateau in the future.