I just did it together with the video and am not really impressed. I think it's a good little workout for people who have no condition at all though. Or for people who just started with getting in shape, maybe.
I try to keep myself fit and in shape during most of the year (except the winter-period) with running, push-ups, pull-ups, lifting weights, etc...
If you want to be in an average (I'd almost dare to say "good", but I won't
) condition, like myself, try building up your stamina with running until you can run 1,5 miles in 15min.
That's what I can do, and I feel like my condition is way too good for this (video) type of "excersizing".
Btw, the only reason I try to stay in shape is to mask the fact that all my true hobbies require only to sit (or lay) in a couch or on a chair (videogames, PC, watching movies, .........)
And it seems to work, too!