Image that you want to have a full-screen hero video that the user can play and pause using controls. Simple enough idea, right? however, because Youtube is technically an iframe, you can't scroll over it when it's embedded. So, if your Youtube element is 100% width and 100% height or greater, the user can't scroll past it unless their cursor is over another element on the site, which is not optimal.
I've seen some sites (The Verge comes to mind) where this scroll issue isn't a problem on full-page videos. I'd love to see a similar fix on Webflow to enable easy, interactive video embeds.