3 minutes and 50 seconds(ish) of trying to explain something incredibly complex in far too little time. Obviously, there's a bit of explaining that needs to be done, especially on the points that he actually does kind of get wrong.
Quick. What is the definition of a creature's sex? Answer:
"either of the two main categories (male and female) into which humans and many other living things are divided on the basis of their reproductive functions."
Okay, cool. But what does that actually mean?
The answer is: Not a lot. Practically nothing, really. Sex is a social construct developed for ease of categorizing individuals (whether human or animal) into two distinct groups. However it's poorly defined and basically morphs into whatever the author needs it to be to define what they want how they want to define it. Let's take Ants, just as an example.
Ants come in four varieties. The Queen, the Drones, the Workers, and the Soldiers. According to SCIENCE the Drones are the only "Male" ants, with the other three types all being female. But since Workers and Soldiers have no reproductive functions whatsoever shouldn't they be sexless, by the textbook definition? Technically, yes, but when it came around time to determine what "Sex" ants were the only question really asked was "Does it have a penis?" because that was the bias floating around the world in those social circles. There was "Has a penis" and "Doesn't have a penis" and that was your sexual binary. Admittedly, there were some exceptions: Creatures that had both got to be hermaphroditic!
And while Hank does lightly touch on the idea of Intersex he doesn't really get into the painful (to biological essentialists) truth: Everyone can have any reproductive capability thanks to modern science. Scientists have found a way to transform skin cells into both Sperm and Ovum. Meaning that a Woman could provide Sperm for a Man's Egg and they'd have a baby neat as you please. Or that a single person of any gender could create both a sperm cell and an egg cell and reproduce all by their lonesome with no one else's DNA involved.
Of course there's also the idea of wider hips or higher testosterone or any number of any other tiny details we ascribe to "Male" or "Female" sex, but those things don't always line up, either. And different environmental factors can alter any of those facets during development. But there's one thing that never changes and marks you indelibly as one "Sex" or the other: Your Genetic Code.
Except that it doesn't thanks to a variety of different genetic structures (XXY, XYY, Etc) and the fact that your genetic structure is about as "Set in Stone" as a puddle of muddy water. See, all life on Earth has something called an Epigenetic Structure. This is separate from your "Actual" genetic code which represents who you are, currently. And everything from a cold climate to prolonged stress can alter your epigenetic code in a wide variety of ways. Behind the Epigenetic Structure is the baseline human DNA that doesn't really define who you are in any meaningful way, but simply contains a blueprint for "Build Human"
My case, for example, involved my mother utilizing a set of hormone boosters given to her by her doctor while she didn't know she was pregnant. As the larger twin in a pair I wound up absorbing more of the chemical mixture and it's very it was a big part of -why- I'm transgender rather than a cis woman. The hormone bath I was in resulted in physical structural changes and frelled my epigenetics, but did not alter my brain-layout which had already mostly formed.
So sex is, essentially, a meaningless part of the video, and all genital configurations should just be ignored for the purpose of determining whether someone is a man, a woman, or nonbinary. That doesn't mean intersex people don't exist, it just means that we shouldn't exclude them from a given gender due to their genital configuration.
But then Hank hits on some big ones! Gender Identity, Gender Presentation, Gender Roles, Sexuality, Sexual Activity, Romantic Attraction, and Romantic Activity.
Each of these details of a person is, as Hank says, on a spectrum rather than on a simple binary switch. But just as important as the spectrum is the understanding that people, like quantum particles, wobble.
So think of the Gender Identity Spectrum Graph. Man on the Left, Woman on the Right. A ten point scale between them and an ten point scale of strength vertically. It's easy to imagine someone as existing as a single Dot on the scale. "Masculine One" and "Masculine Strength Ten". But every person has the ability to wobble on the graph. To go up, down, left, or right a short distance on the scale on different days or different hours. Masculine One/10 might shift over to Masculine 3/5 on days when he's not feeling -particularly- Manly Manly and feels like he wants to put on a nice suit and treat himself to dinner. You get the idea.
Some individuals, particularly those close to the center of the Spectrum have a tendency to wobble much further. Feeling Agender (right in the middle of the graph) with a score of 0 one day and then swinging to Man 3/6 or Woman 5/2 on the next day. These wobbles represent a person's shifting moods, personality, interests, and in some cases identity. It doesn't make a woman any less of a woman if she has a "Man" day. Nor does it make a Man less of a Man if he has a Man 3/1 day, when he doesn't feel particularly manly.
Which actually leads us to the next item: Bisexuality is terribly defined.
Like Homosexuality, Bisexuality was initially created by someone who wasn't bisexual trying to encapsulate someone else's experiences into a single word based on their own understanding of those experiences. This lead to the idea that bisexuality is Man/Woman attraction. As described by bisexuals, myself included, bisexuality is closer to being attracted to "Two or More Genders". While I'm typically comfortable explaining to people that I fall under the "Standard" definition of Bisexuality I'm also very attracted to Androgynous people who lack gender. I'm not Pansexual, because I don't feel much if any attraction towards Demiboys or Genderfluid individuals, but agender are pretty sexually appealing in their own right. And that's an issue that bisexuals have trying to explain their sexual attraction to people who are hung up on latin terminology created by people with only a rudimentary understanding of what is -actually- happening.
Similarly, I'm married to a man. This does not make me Straight, even though I am in a monogamous heterosexual relationship. I still feel attraction to Agender individuals and Women (trans or otherwise). Because sexual behavior does not supercede sexual attraction, it's just a different spectrum of being.
Meanwhile I'm Panromantic so... y'know. That's fun. If I ever wound up in a relationship with a Demiboy or a Genderfluid person I wouldn't be sexually attracted to them even though I was romantically tied to them...
So. In summation: The video is for the most part really good at explaining the spectrums of human relationships, identities, and sexuality and how those things are complicated. Even with the problems listed above I still recommend it -very- highly as an introduction of concepts.