Having not joined the community until three years after the film in question was released, I have been forced to conduct my own research as to what makes this film so special. I have not had this information verified, so if I am wrong, please correct me.
The root seems to be in the original thread on Brickfilms.com where Tim makes a post on page 2 declaring how awesome the movie is. From there on in, various people begin to jump on the COTY bandwagon (the first being Dragoon) and it escalates from there, with the pro-COTY and anti-COTY movements developing amidst this discussion.
Oddly, KG, today one of the top supporters of Septemberfest, remarked
It's good, but it's not THAT good.
Original post.
Also, claims that Watson is actually KG in disguise can be laid aside because I am still a moderator on the site and can see that they have never posted from the same IP address.
Like I said, this is only what I have gathered and if anything I have said is incorrect, please put it right.