Back in the days of TTV's basic YouTube channel (a week or so before the Boards), I saw Pot8o comment somewhere. I think that's when I started idolizing him, all until his 95 spam pics on Skype.
I've seen Cordak here and there; first in the YouTube comments of a Tiribomba skit (before he joined the boards; I thought it as nothing at the time) and now everywhere on youtube, including the top comment of the Honest Trailer for Ep. III.
I've found MFS's YouTube channel and G+ page, and the top comment of the Luke is Evil Game Theory.
That's about it for now, frankly.