Quite enjoyed watching the video which gave me some food for thought.
How I see things is that you'll have a little less or a little more smoke into your "clouds", depending on your shisha and heat management.
I don't believe it's realistically possible to have zero tar or zero smoke (also regarding glycerine, which from my net searches seems to be impossible to vaporize it without partly burning it). Unless maybe if you throw a some water into your bowl.
Btw, box says zero tar, because there is no tar inside, before heating the shisha
Seems tar can happen at much lower temperatures (400 degrees - hit "Creosote" on Wikipedia for more details).
I am sure there is some tar in there, but using a hose for few hours isn't going to show it.
Another possible source of concern are the chemicals they use for flavoring the shisha.