that moss is called ''pillow moss'. its a terrestrial moss that likes bright light and a moist wet and cool enviorment. you can usually find it in most chain pets stores dried. the dried stuff will come back. also if you throught the dried pillow moss in a food prossesor and make it to a powder.tthen soak the powder in cool water so it makes a paste and spread it over the substrate. in no time you'll have an awesome moss floor. just dont let it dry outthat looks sweet.
I've been looking for something more like this though... to cap the substrate.