The interesting thing is to watch for all of the "dominant" body language especially from Seven. She places her head and paws on the back of Riley frequently. Tails are high. Seven and Riley will often freeze before they explode. But it is all in play.
If you have a hard time reading body language, look for it in these clips. I would never allow my girls to greet a dog (especially on leash) with a stiff tail held high or vice versus. Also, you will often see a moment when the dogs freeze before a fight breaks out. You want to avoid those and interrupt if it does happen.
And this would be why I am waiting for Maddie to be full grown and coordinated before tangling with these girls off leash.