Is this guy for real? He'll teach you how to ride a mountain bike? While it's pretty enterprising it's also hokey if you ask me. Save yourself some coin and just ride with someone who is better than you and knows what they are doing on the trail.
If you can't change a flat while on the trail, maybe you shouldn't be riding but you can go to your LBS and have them teach you how to fix a flat. Experiment yourself, too. If it wasn't for trying new things, I would have never been able to fix a flat I had commuting once and would have to hung my head in disgust and limped home.
Now, is this guy really a mountain biker or just a roadie who rides mountain bikes? I am all for spandex for races and quick workouts but come on, where are the baggies? And where is the offer to teach skinny riding, rollers, and hucks? Maybe that's part of the package deal. Of course, Long Island being flat and unchallenging might not have any of the fun stuff.
I guess it's not unheard of, paying for riding lessons, Middlesex College in Middletown, CT did something similar this past summer.