Cool video. Kind of bummed that they continue the popular but incorrect visualization of the Big Bang as an explosion from a point, though.
Added: Since I was asked on Discord what a more correct visualization would look like:
A more correct view should be rendered from within (there is no outside to view from), with Big Bang appearing as a uniform expansion everywhere, in accordance to the cosmological principles of homogeneity and isotropy. The universe would at first look like a very dense and uniform fog in all directions. Then as it expands and cools you would see farther due to the decreasing density. Then reionization happens (electrons bind with nuclei to form atoms, universe becomes transparent everywhere, CMB is released), and your visibility then extends outward at the speed of light. Over time the small density fluctuations are also collapsing gravitationally, and so eventually you observe the cosmic web structure forming.
Very few videos accurately portray all of this (particularly the increasing range of visibility), but this is one of the better ones that I'm aware of.
Good (but technical) lecture on early era of star formation. Normally I wouldn't link one like this, but I really liked the discussion on the role of cosmic dust, and why cosmic dust is interesting. (My advisor when I lived on the east coast specialized in the physics of dust and it rubbed off on me as well.)
Another interesting topic is the use of gravitational lenses to resolve even more distant objects, and the reverse, where lensed background sources act as a way to determine the lens, which in some cases even lets us resolve the sub-structure of dark matter halos.
We have a meteor camera not far from Abisko, but I discovered that the file server's smbd process had stopped, so nothing was recorded. The spooky thing is that smbd had stopped at the very same time on half of our servers across the country. I've never seen it stop unexpectedly before. And certainly not in a synchronised manner on totally unconnected computers. A clock related bug in smbd? Knocked out by a solar storm? Really spooky action at a distance. Especially since it happened early yesterday morning, minutes after the death of Hawking.
It's slightly worrying that whenever theory doesn't match observation, the reflex is "it's dark matter/energy"! On the other hand, the more times scientists play that card, the more has to be consistent, which either means that we can better explain dark matter/energy or that the explanation is wrong.
That dark matter might explain the depth of the absorption feature is a hypothesis being proposed by this particular group. The cosmological community is not yet convinced that this is the only thing that could explain it, or even that this explanation is actually consistent with dark matter models. So this is an important observational discrepancy which will lead to a period of model testing, to see what best fits the data and predicts new data. (And as you say, they must be consistent!) At the very least we stand a good chance of refining the LCDM model from this observation, and that would be exciting on top of the detected signature of the first stars.
For other observations that have been attributed to dark matter, these are not so much a reflex as an understanding that has been built up over several decades of model testing. A scientific community does not get convinced by a model because it can be fitted to data. They get convinced when it is the only model that correctly predicts a new observation. The keystone observation which convinced the broad cosmological community that dark matter better explains observations than modified gravity was seeing the predicted separation of dark matter from regular matter in colliding galaxy clusters. There are now a few other predictive successes as well, like the observation of dark matter sub haloes (previously linked video), and the correctly predicted 130GeV gamma ray excess from models of dark matter annihilation.