Does anyone know how he did it?

I was watching a Chris Ramsey video https://www.youtube.com/watch?v=qme-DS9EaUA&list=PLNZrOW6Nuocqi7SNA3cKMhXB4k17vaSyB and I think he explained the last trick at some point, but I can't find it. Does anyone know what the trick is called or anything? Thanks a lot, folks, cheers.