Took a look, seems to me like the title is a bit misleading. Maybe I'm mistaken but from watching the video I don't get the sense that this copies 'React code', from any site, it just takes a section of the dom from any site and copies over the relevant css and js. I think something like this is going to take off though, as frontend devs we keep reinventing the wheel needlessly. You should be able to point to a site, any site, and basically clone it. Generate a suitable backend while you're at it. Do a style transfer. So say I want to have an ecommerce shop in a certain niche, point to an existing online store, do a style transfer, and boom you have the same functionality just with original content and style.

Addendum: Figured I should give it a try because I think the idea has promise. But I tried this on three sites, a regular js site, a next.js site and a CRA site. Each time tried to do a 'Copy React' op on a button, and each time I just got back html.