I found this 4 part video about MTHFR and it really helped me put a lot of this together after 2+ years of reading about and treating CFS with b12/methylation. I think it is a must see for anyone looking into this. I don't think he has all the answers, but you could show this to someone off the street and they could gain a basic understanding of what is probably going on with methylation. I would suggest pinning this at the top of this forum.
http://www.methyl-life.com/a-doctor-explains.html
http://www.methyl-life.com/a-doctor-explains.html