WHAT is this, and WHY do you want it under your floors?

In this Video Matt reviews the Schluter Ditra underlayment system. https://www.schluterevents.com/en/north_america.php This is the event website Matt refrences. More info on Ditra at their official website here: https://www.schluter.com/schluter-us/en_US/Membranes/Uncoupling-(DITRA)/Schluter%C2%AE-DITRA-&-DITRA-XL/p/DITRA For some general pricing here's Ditra XL on Amazon. https://amzn.to/2EAOt71