We did the keys tour in 2001 and it was great. The underground (first floor) part of the tour was about half an hour to 45 miutes. We saw the sewing room and much more.
We also went about a year ago and it was nowhere as good. For the tunnel part she led usdown one tunnel and we stopped and watched a tv with a video about something. Then we went back up and saw where tinkerbell lands during the fireworks. That was all the backstage part. The tour is just not as good as it used to be.
Mikeeee
I had asked about changes, and they said that they do change the area of the tunnels that they go into every now and then, but denied that after 9/11, they were intentionally keeping people in only one section.
We originally went backstage behind Big Thunder Mt, and later went backstage via Main St (the Emporium side, I think) and probably went down the same area as you, but we did walk a
little bit of tunnel, and there was no video. But we were down there for probably 20 minutes or so. Certainly, I'd love for it to have been more extensive, and even have started in one area and popped out in another, but overall, it was still a fun, entertaining, and educational tour... I'd do it again in a moment.
Mostly likely, I'll probably do the big 3-park backstage tour next, though the price is a good bit higher for not much more actual tour time. I have no idea when that'll happen, though - it's hard taking something like that with a little kid to take care of.

(We were able to pawn him off on grandparents that day last time!)