But how can a cat be in two boxes at once? A box in a box?

The video simply gives background on the original Schrodinger cat thought experiment. The article goes into what scientists are doing now.

Darn. I was imagining the cat getting into the box. 

A NEW KIND OF CAT

Okay, so that’s the basis of the Schrodinger’s cat experiment. Researchers have now taken it out of the hypothetical realm and performed it in the lab, not with actual cats, but with electromagnetic waves in the form of microwave photons.

Just as quantum particles can exist in superposition – which is what gives the whole cat experiment some practical applications i.e. computing and understanding the behaviour of the smallest building blocks of the Universe – so too can electromagnetic waves.

Photons can be polarised both vertically and horizontally at the same time until someone actually measures their polarisation, and microwave photons can be coaxed into this cat-like state too.

“Normally, electromagnetic waves in the box will oscillate in strength, like a pendulum sweeping back and forth,” Joshua Sokol explains for New Scientist. “But it’s possible to introduce the opposite wave into the box, creating a cat state that is doing two seemingly contradictory things at once.”

That’s what a team of physicists led by Chen Wang from Yale University did to demonstrate the basics of the Schrodinger’s cat thought experiment in reality. “A mechanical analog of this would be a pendulum that is simultaneously oscillating to the left and to the right,” he told Sokol.

They really confuse this whole issue by making us think of cats. 

And guess what, Adam... "But once they’d got that down the team took things one step further, by asking, “What if there were two cats?”

I'm liking that idea.