This is a guess, but think it's reaonably accurate (I've dappled w/ voice recognition
technology off and on over the years). We spent a couple of hours
at the Innoventions Stitch last year (w/ two kids) w/ me trying to get a peek behind the
curtains while we waited!
There's CM behind the screen w/ TV camera looking at the audience (in
DL, this is the one that escorted you in) and a sophisticated computer that changes the CM voice to that of the character & CM also controls position and motion of CGI thru joysticks and recorded motions
I suspect that the Crush one is very similar. Also notice that there are certain actions
that always happen and they're exactly the same at the same positions. Actually, Stitch
is easier since he's got a gravelly (distorted) voice. It's neat that they could do the
same w/ Crush.