Originally Posted by oldbobcat

Basically, your body tries to balance itself over your feet. The lower you drop your torso, the farther back your hips want to go to avoid falling on your face, or at least doing pushups with your arms to support it all day long.

My only suggestion is, by increasing saddle setback you are increasing the distance between the butt end and your pedals. Instead of increasing saddle height, you might want to be decreasing it. Or perhaps your bike dealer set the saddle a little low in the first place to accommodate your beginning skill level. I can't see you on the bike, but if you feel like you have to rock your hips or point your toes to finish the stroke, or if the saddle feels like it's driving a wedge up your perineum or you feel out of balance, you're probably too high. And a little too low is better than a little too high, especially on a mountain bike.