The moss in that thread is Sphagnum Moss and can be bought in a brick form just like Eco-Earth comes.
You don't want this or most loose moss as a top layer because it is an impaction hazard. Easy for a frog to swallow and have turn to a knot in its stomach. i do like to use it as a layer below the soil to retain moisture.

Sheet moss/Tropical moss is a small moss that many use as a top cover layer. It is bought as a sheet and the whole sheet can be laid out on top of the soil. I used this but always had trouble with it living and growing. Mostly it turned brown over time and the I tossed it and replaced.