I find the interesting bit is really this:

if we calculate the size of a black hole with mass and energy equal to all the mass and energy we can see in the Universe, we get a surprising result: it’s almost the same size of the observable Universe!

If this seems odd, remember that a black hole’s radius is directly proportional to its mass, while its volume is proportional to its radius cubed.

Kurzgesagt has a good video about this: https://www.youtube.com/watch?v=71eUes30gwc

Perhaps we're living in a black hole within a black hole!

Or worse: it's black holes all the way down!

plot twist. it is the black hole in the center of the galaxy

so we are inside an object that we can observe looking outwards to the stars

shouldn't that be "all the way up"?

Thank you, both, you are probably correct.

I suppose it depends on where you're standing.

I’d go with “all the way out” in this case.

all the way either way!