Pretty entertaining!

Jumping up on my soap box for a moment:

This is a nice example of why lessons in 'Setting boundaries with dogs - 101' ought to be taught in school and refreshed annually till graduation, not unlike fire safety. If these guys had known how, it would've been simple to shut down what began as a mild case of normal curiosity. However they (apparently inadvertently) repeatedly invited the dog to intrude further instead of communicating that the behaviour was not acceptable.

It's an ongoing mystery to me how members of our society, in which dogs are so prevalent, can be so unskilled in managing even mild behaviour errors. (Yes, the behaviour may be natural for a dog, but in the human world there are rules to be followed and not following them is, to me, an error of behaviour. Of course the primary behavioural error was made by a different human: Failure to use a leash!)

Okay, jumping down off my soap box now!
:-)