Ah...
Okay, now I follow you. Yes, there usually is a bit of a spike of interest when the DVD's come out in regards to the extras, but I don't know just how many folks [number of fans interested in DVD talk vrs the baseline number of all Stargate fans] who go out and buy the DVD's, vrs. those who tape the eps, just download the 'squinty vision' off the net or not archive the show all together]. The percent of DVD's buyers vrs everyone else just may not be high enough to kick-start a lot of discussion. I know I'm archiving the DVD's. A percentage of my fan friends aren't because of the overall cost.
I've found the same to be somewhat valid in other fandoms I'm in. Such as "Babylon-5", "Firefly", etc. This is my experience. It's not something I can quote cold, hard facts about.
Now, as I understand it, the usegroups/newsgroups run to a different demographic of 'discussion' [like alt.rec.stargate, for example] and you may find what you're interested in there. I'm not a usegroups user, so I'm not much of a resource there.
Rowan