You really don't even have to call your dogs away. Some people have said distracting the dog may be dangerous for the dog. If you just started making yourself look big and yelling at the mountain lion, anything you could do tower lots of noise, fire a gunshot, bang on pots and pans. Wild animals have been kind of naturally trained to avoid humans and human populated areas. While they may be bold defending their turf to human intruders or curious enough to roam into our area they know better than to confront humans. And even if we say "well the dogs and mountain lions don't look like they want a fight, if that mountain lions as "small" for it's species it may be would seriously harm one of those dogs. If that guy put down his camera and went out yelling at the lion along with the presence of those dogs I bet that thing turns and runs.
On a side note it is interesting to see how domesticated dogs stl have that natural instinct to surround and pester a larger animal, staying aggressive while still knowing not to get in too close.