I've found that the instructor quality can really vary. There's one I hate... she's a "stand up and mash" type and I uttelry refuse to mash my pedals. Many time I just close my eyes and visualize a favorite section of single track. Also, I've been experimenting with keeping my heart rate lower ( 140) al la Lance's training instaed up in the 80% range.

As for the getting your butt back thing.. if you do it right, with a very quiet stable core, my experinces is that you are really isoloating the butt and quad muscles.

penny