I'm going to go through a few of the claims he's made ignoring all of the over the top, anti-religious crap.
It's difficult to know if some of these are slip-ups or genuine ignorance. They're not the kind of mistake anyone with an actual understanding of the topic would make. He equivocates for example between "expansion" and "inflation" as if they were the same thing. Inflation was first proposed by Starobinksy and Guth in the early '80s as an add-on to the Big Bang theory. A universe inflates when:
Where a is the scale factor of the universe. It wasn't discovered alongside the redshift of galaxies and it's very much a different proposal to the expanding universe (which is described by the first Friedman equation):
Without an added term, there's obviously nothing in this equation which requires the first to hold. If this were the only mistake, I really wouldn't care but the video gets worse, a lot worse.
You can tell in the video that he accepts that time had a beginning, yet he's apparently unsure if the universe had a singularity. It's true that singularities are very controversial, but there is only a beginning of time if there is a singularity! There is no beginning of time in geodesically complete spacetimes.
A singularity is a boundary to space-time, it appears when the world line of particles terminates in the finite past under the effects of gravity. Therefore the metric equation of GR breaks down and that's what it means, to have a 'beginning to spacetime' because you cannot extend a geodesic beyond a singularity. In almost every non-singular model time t stretches back indefinitely, to minus infinity.
What's more, physicists don't know everything else in "spectacular detail" that claim is just odd. What exactly does AronRa think physicists actually research? The measurement problem, quantum gravity, the transplankian problem, the cosmological constant problem, the measure problem, physicists are still in the job because there's still a lot more to be done. Look through any journal in physics.
The vacuum itself has a beginning if the universe is singular or past incomplete, and it is in several constructible models that General relativity allows.
When a cosmologist says "nothing existed before the Big Bang" they don't mean there was a very thin kind of something, like a vacuum. They mean there was no "before", time breaks down on the standard FRWL model and it doesn't make sense to talk of anything (even a vacuum) "prior" to the beginning.
It gets difficult to follow later on because AronRa obviously doesn't know what he's talking about. He uses words like "boundary" when he obviously means a universe without a boundary, and phrases like "matter and energy" when he apparently means "mass and energy".
AronRa's commentary sounds a lot like someone flailing around grasping onto whatever buzzword they can drop in the middle of a sentence because they're lacking any substance. It only gets remotely sensible when he suggests that there could be a multiverse, indeed this is about the only true statement AronRa has made, but he's now dropped his requirement for testability and falsifiability. There are very little cosmologists can do verify or falsify the existence of other universes and the most fashionable version of the multiverse coming out of inflationary theory cannot be past-eternal, when you integrate over the Hubble parameter it's below some finite bound. So that too involves a singular beginning.
Almost every cosmologist alive today, every textbook on astronomy, every basic introductory course on astrophysics will tell you that a singularity represents an absolute beginning to the universe. AronRa disagrees. He says, and I have no idea what he's talking about "one second stretches out to equal infinity" at the singularity but that clearly doesn't follow from "time has a singular boundary" and again he's not getting this from any actual cosmologist. He's just making it up.
What it means to say "time had a beginning" is exactly the opposite, it means the universe had a beginning.
Worse than that, he thinks not only that matter and energy can somehow exist without time (they can't), but from his description, he clearly doesn't understand what energy and mass even are. In classical mechanics, energy is defined as 'the ability to do work' and mass is a measure of how difficult something is to accelerate. They're not some corporeal substance like matter (which is what he thinks they are). I'll bet this is all well explained in the high school physics course AronRa obviously failed.
Using classical theory (contrary to what nonsense AronRa says 6:42) we can follow the world line of particles with mass back and they terminate at a singularity. This result was very famously shown by Penrose and Hawking in the late 1960s. Again, it's painfully obvious that he doesn't know what he's talking about.
It also doesn't take much to disprove what AronRa is coming out with about entropy at 6:46. Entropy is the logarithm of the total number of ways a systems atoms can be arranged. That is
At this point, I got rather tired but thankfully he's stopped making ridiculous claims about physics.
Dear AronRa, if you are reading this and somehow managed to take a break from telling us how ignorant and stupid you think religious people are, perhaps you should study up on physics. This is one of the worst videos I've ever seen, your understanding is, it's fair to say, behind. Maybe this was meant as an early April fools joke and I didn't get it. I don't know but seriously, fix that.