I used tear-n-tape all the way to the edges but after a day or two it curled up. Since then I found the Stampin' Seal + to be strong enough to keep the vellum from curling. Great question!
Hi Dawn. I forgot to mention it in the video but added it to the description. I find that a strong tape runner like the Seal+ works and it doesn't show through. Just be sure to get the adhesive all the way to the edge to help keep the edges that want to curl down securely.