Lisa, I've just looked at the video - I've not seen nor used this frame.
You would need to be very accurate when pushing the fabric into the slots that it was absolutely
on grain. I see this is a problem especially with canvas.
l that the side of the fabric is lashed to the side bars so that tension is evenly applied. As shown the sides would flap.
So... in my entirely personal opinion I would not waste money on this frame.
The correct term for 'Roller' frame is actually 'Slate' frame. They come with lots of different variations; some tighten the side bars with a screw, others need cotter pins. I have both..
But they all have a tape on the roller to sew the fabric to, and strong side bars for lashing.
Attaching the fabric is called 'Dressing a slate frame' - google that to see lots of ideas.This
is a rather long-winded one that I came across.