CM - That's the long down. In the BH the handler leaves the dog as in goes out of sight until called back by the judge.
There are reasons to train for this and there are reasons to not do it in real life. Depends on the dog, the situation, the handler -- all situations require evaluation.
Once a well meaning person decided to walk my dog when I had left her in a down stay. She got an earful from me.
Yes it is the "Long Down" and a fun exercise to train a dog for, esp. when the two dogs are good friends. Great distraction!
Doing it "in real life" whatever that means to anyone - in a public street, in a crowded training class, in a crowded back yard, in a parking lot, vets office or anywhere; to me is a great way to "Proof" the stay behavior.
Of course i would never recommend that anyone do it where their dog could be in danger! That would really be stupid. Like having a dog practice a stay right next to a busy highway!!!!!!
Having someone try to walk your dog - WOW!
I can imagine what I would have said. I don't think he would have went with a stranger however, but from the looks of my old guy I don't think that very many people would have tried to pick up his leash at any rate.