Difference between blowing with air and floating with water. Relining Microducts into Ducts

How to use existing infrastructure in the ground? Many places there is already 40 or 50 mm. ducts in the ground that can be used for further installation.
Here we show how to do it. This was in a customer case where we wanted to counsel a customer in a situation where we would like him to change his opinion.
How could we do this better than to demonstrate this. See our learning's and see the conclusion.