There's a little bit about it on the 'backstage' part of the extras on the DVD too. Just them rehearsing the Kermit. You don't see Steve at all but at one shot during rehearsals the cameras in the audience and looking down at the stage and there's a little group of people standing around where Kermit was going to be on the amp and I'm pretty sure that it's Steve you can just see but as there's a woman standing in front of him talking I can't be 100% but pretty sure it is cause you notice the long hair.