I agree. Beginners cannot become proficient in any art training by themselves. I had a guy try to tell me he was a "black belt level ninja.". I asked who he trained with and he told me that he went to a few sessions with a master "in the park" and learned the rest from videos. I laughed out loud - couldn't help it. He got offended. I offered to work out with him if he wanted but he never said anything. I'm sure his techniques were too deadly to share. Old secrets that I'm not worthy of because I didn't buy those videos.
I would think that grappling would be even harder to learn without a live coach and people to train with.
I've learned most of my bjj without official classes. I'm lucky enough to be invited to an open mat with a lot of guys from a great school. Also a few of the the guys at the karate school are very good with bjj and I roll almost every class. I could never have any level of understanding without those guys. Would like to drill more though.
I am here: http://maps.google.com/maps?ll=39.938739,-75.065198