SmartPolician:
That dude doesn't look like the groom. He's probably the bestman or someone important in the groom's team.

If that be the case, I think the bride is just trying to maintain some decency in her wedding, knowing very well that a cameraman is filming everything.

I think she knows that she has wayward friends and doesn't want them to display their madness in her wedding reception. Consequently, she stopped the lady from rocking the dude.

Maybe...