Hi,
That is extremelly thick velvet, and the same that I used for my cape.
You can buy that material (and make your own drapes!!!!) at any theatrical supply material stores, and there are some in Hollywood that carry the material. If you have a business license you can get these wholesale ... !!!
The difference? ... usually it is 48 inches wide, instead of the lesser width that you can find in most stores. It is cheaper all around.
You do want to loop these a bit and make one of those waveform like things to help catch the sound, and you want as few seams as possible, to help the material be stronger and last longer.