They do not leave the contained box, but the box moves forward.
According to the diagram, there is nothing impeding the EMF from escaping out the rear. However, it isn't doing something and then nothing coming from it. They claim more of a reaction than I would expect, obviously. That's the opposite of what you stated. Did you just misstate?
"...shows a action, without a equal and opposite reaction."
Again, that mischaracterizes what is claimed. What is claimed is that the high EMF affects the vacuum pressure and mechanism whereby inertia inures to mass.
I do not have a closed mind about novel mechanisms being potential, and not even those, like the one I posted, that are very outside traditional physics. But, it is factually incorrect to say that something comes of nothing, that action produces no reaction. Cause and effect may break down at some point, but I haven't seen any evidence of it, despite speculation to that effect being a constant.