The actors are appearing for the first time except Michelle, that I think was the little girl in Full House. And when they say her name all look to the camera in a funny way at the same time. They say something about her like she's running a fashion show. What was that all about?
This was a case of fourth-wall breaking. The fact that the Olsen twins were not joining the cast of the show had been widely reported during its development, which meant that Michelle would not be appearing. So, the show needed to come up with a reason to explain their absence.
As it turns out, Mary-Kate and Ashley do have their own clothing line, so "running a fashion show" is a reasonable (though not true) explanation why the actresses were unavailable for the program. The writers merely applied that same explanation to the characters.
The actors all looked at the camera as a "wink and nod" to the audience that they were aware of the double-meaning of the dialogue, and that it was intentional on the part of the writers.