Well.... the video sound is god aweful to begin with.
Second point is, perhaps the on stage monitors may not be very good either, had that happen performing myself, can't hear the band, can't hear yourself coming through = suck.
My last point would be that the video is shot from 3 miles back.
So add em all up and that's what you might be seeing, because as musicians,
I've seen Extreme before open up for Whitesnake and they were rippin it up.
This is the equivilant of seeing Nick Nolte falling down piss drunk and crapping himself. You like the guy, you think he's a great actor, but he's not at his best right now.