In this video I've seen, it's in a different language, they  are using this thing. It looks like a springform pan. But slightly different. 

I'm hoping someone can watch the video and tell me what it's called. 

Thank you in advance 

https://www.instagram.com/p/BQVc62pAHaU/

You can purchase cake rings....they are metal without any top/bottom - just an open ring of metal....that one has a buckle on  but not all of them do.   Just push your layers into the ring. 

Some bakeries use them to actually bake in by placing them on a lg baking pan/sheet.  I had some but can't remember where I purchased them.

Yes, it's an adjustable cake ring, like kakeladi said. The adjustable rings can be used to make a variety of sizes. 

I've never seen it used that way, people typically bake or build cakes inside them (not that it's wrong-whatever works).  Some people use a taller pan, like a 3" or the cake pan plus acetate for a taller cake- like Milk Bar style cakes, they bake in a sheet pan and use the rings to cut out, then build (as K said). 

In the video, it looks like they used a smaller size to let the gelee setup in (just a guess on the filling) you could do the same in cake tins if you have enough or spread it out (the process I mean).  Wicked Cake Co ( I think that's her name, she works with modeling chocolate a lot) she has a blog, video tutorials on 'How to Build a Cake' but she uses her cake pans. 

Try searching for adjustable mousse mold/mould or adjustable cake mold/mould, that's how I've seen them before.