Is it possible to use background matting in blender (without green screen of course)?
you mean like the original matte paintings on glass which where positioned direct afront the camera while showing a big castle in the background ?
well with blender you can do a 2d tracking of that background and even compensate camera movments.
search for 2D camera. search for ‘blender camera 2d tracking’ () and … even back in 2016 blender could do this: OpenVisualFX 2D tracking (2016).
Or short: Yes, Blender can.
I mean this:
It seems to be that you already have a source. Even a video. Wanna share ?
edit: Ups 
this is a link …
Okay this is just five month old on Github: Just use it.
Jokes aside, maybe you just want to photograph your background and if it’s an given Video: grab the pieces from the background if you see them, stich them together and…
at 0.38 he say this technics is not new and there is a text : “bg that i photoshopped”