There's quite a bit of Boston live video out there, but because all of it is fan shot, consumer camera stuff, the quality is all over the place.
This is from the Third Stage tour, and the sound is actually pretty good since it's nothing more than a hand held microphone.
Unless Tom Scholz opens the vaults and releases the video from the '88, '94, '97 and 2003 tours this is probably the best you're going to get.
One more time. An encore of one of the best voices in rock:
Brad Delp - Peace of Mind
'til the other side
Keep the Adventure Alive,