Apparently that video was filmed a while ago too, so you're not even seeing a polished final product.
From one of they guys at Harmonix:
Hey all
This video was taken from a conference where attendees are generally encouraged to be casual and show off the new stuff they are working on privately. Unfortunately, an attendee broke the conference rules and videotaped the talk. The footage was made from an old build of the game quite some time ago for internal purposes- basically to get people working on the game excited. The song was one we have considered for the game but haven’t locked down, and you may have noticed that the footage was made so long ago that the people in the video are playing old instruments and prototypes. I guess what I am saying is- this isn’t official and doesn’t really reflect the final game at all. We’ll be releasing a lot of info next week from much newer builds of the game with finalized songs.
Rock,
Sean
So if all that stuff was old news, imagine what the final game is going to be like!