I mounted my velvet 7 years ago on my walls and ceiling using thumb tacks temporarily to see how velvet would work. It's still like this today.
Some day I plan to get some 1x1's and roll the top, repeat on the bottom and stretch the velvet and screw those 1x1's to the to and bottom corners.
I don't think staples would show up. If they did you could sharpie over them.
Video: JVC RS4500 135" screen in pure black room no light, htpc nvidia 1080ti.
Audio: Anthem mrx720 running 7.1.4, McIntosh MC-303, MC-152, B&W 802d3 LR, B&W HTM1D3 center, B&W 805d3 surround, B&W 702S2 rear, B&W 706s2 x 4 shelf mounted for atmos, 2 sub arrays both infinite baffle: 4x15 fi audio running on behringer ep4000 + 4x12 fi audio running on 2nd ep4000.