The key to getting along with anyone is to match the energy of the other person. That means if they are loud and boisterous, match their loudness and boisterism. If they are quiet, match that quietness. You'll have two friends for life. One will be an annoying loud guy and the other will be an introverted creep, but at least you'll have friends. I never mentioned the quality of friends.
This baby is using that tactic to bond with the family dog. That's a smart baby to think, "Ok, if this thing is going to pull on the rope with its mouth, I better do that too. I don't want to fall out of line with what's going on, you know?" That's how I imagine a baby's brain works. We'd never know because children lose their memories at age three.