Yes (and no)! It doesn't "stop" the transmission of sound waves, but it certainly greatly reduces loud noises like stomping and speaking in the rooms below.

Evet, gürültü de duvardan geçiyor. Bir sonraki adımda döşemeyi tamamen duvara doğru itmeyip bir boşluk bırakmamızın nedeni de budur. Bu şekilde zemin kaplamasını duvardan mümkün olan en iyi şekilde ayırırsınız. [Google Translate]

The mats are a mix of rubber and kork.

The only way to effectively reduce very low frequencies is with MASS - a lot of it. A thick layer of Concrete works wonders when it comes to frequencies under 100 hz. That said, the sound insulation we use in this video does not work as well as concrete - it just doesn't have the mass to do the job. It does, however, gently cut into frequencies starting below 100hz, gradually increasing its effectiveness the higher the frequency content. Hope this helps.

We installed hardwood flooring on top. We show the process in step 3.

Thanks for your comment. As you've pointed out, some older and lowerer quality flooring adhesives (most of them are not sold anymore) used to smell really bad and could potentially be poisonous if inhaled for a prolonged period of time. Luckily, with technological advancement, we now have products that neither smell bad, nor affect health negatively. We wouldn't have our customers - or personnel, for that matter - come in contact with dangerous materials or substances.