What's going on here? I get that he's checking the model to the reference. But the series of facial expressions she displays near the end is very hard to read; initially a light smile, then maybe crestfallen (as if she's responding to the artist's expression of disappointment), then worried (like she's afraid she'll be deleted), then she spasms.

I guess she could just be sneezing.

I think she's trying not to laugh and then bursts out laughing at the end.