If you become your dogs leader then you can stop this.
You just say 'no' or stop it. It is not good for your pup as he will meet his match and then there will be a fight on.
The lady is pretty bad allowing her pup to be dominated like this.
At home or out side, I try to stop any humping, fighting, posturing, or any sign of dominant behavior. The dogs are not allowed pick on something weaker or I will pick on them.
It is not easy. I'm not sure why the dogs go and lick the others faces but i find usually the more dominant dog licks the faces of the lesser dogs and the weaker dog turns away.