If you go down to the mall you'll see those things hanging in almost every window display.
The bad news is, over a very short time they impart a ferocious curl to the unsupported vertical sides of the print. OK for temporary use as in the rushed show described in the video, but you'll lose the print sooner rather than later from stretching that affects the centers much more than the sides.
Most of the ones I've seen have been made of aluminum. Wood is of course not supposed to touch the print, but for an unprotected print displayed open air style that's the least of your archival worries.
I have made gallery show window banners by sandwiching the tops and bottom of prints between 1/2x1x36 inch "craft wood" bought at Lowes. Poplar and Oak are good choices. I just drive a short brass screws front to back, best if you pre-drill pilot holes. Works OK for a month or two, but the banner is basically warped trash afterwards.