Hey all...there are lots of visual effects artists and filmmakers around these parts. I wanted to pick your brains to see if you could help me with something.

This is a scene from "Bride of Frankenstein". I tried searching the interwebs to see how this scene was shot, but came up empty. So I thought I'd ask y'all if you had any idea how this was done (in 1935), be it deduction or if you can find an article that explains it.

There's a part, when the king escapes and runs behind a teacup that there is some clear black marks along the edges of the cup. Same goes for when he hops over the smoking pipe. But the fact that they are glass jars and you can see Doctor Pretorius' movements through the jars...it just looks incredible, even now.

Thoughts? Is it just insanely meticulous film-negative layering?