So, the headline is quite wrong. Nothing in this work has directly to do with our universe, nor does it show that we live in a hologram. What it does do is provide some further evidence for a string theory conjecture called AdS/CFT. This conjecture says that "string theory in d dimensions" is precisely the same as "conformal field theory in d-1 dimensions". This is cute, since it lets us calculate some things, for example, one might be interested in calculating something in some field theory, but it is very difficult to do. AdS/CFT lets us translate that thing into a string theory thing, which usually is easier to compute. So people working in condensed matter physics, particle physics and QCD are actually using this string theory conjecture as a computational tool. However, AdS/CFT tells us nothing about our universe, since we know that the type of string theories it talks about can't describe our universe. So it is "only" a useful toy model and computational tool. The article is about that some guys have run computer simulations to calculate something on both sides, so both on the string side, and in the field theory side, and what they get match, as it should if the conjecture is true. This is nice and lends further evidence to the conjecture, but there is plenty of other evidence already known, both numerical and theoretical. So I fail to see how this is important or newsworthy, it feels mostly like useless hype.

Nobody is saying that the universe is precisely a hologram stored on a flat plane, so before you call it horseshit, you could try to read what they are actually saying. Also, the particular theory they are talking about here has actually been tested, at least somewhat: people used it to compute some stuff about gluon plasma, which they then tested against LHC data, and it matched quite well. So the theories do work, and they can be used to compute real predictions.